Out of ideas? Don't worry. Roll d100 and check this table out for various inspiration for plots, adventures, campaigns, scenarios and what-not.
01 - Labyrinth. There is a labyrinth with many levels, treasures and dangers. How deep you dare to travel and can you find your way out? There is a huge strange and dangerous monster in the middle with greatest rewards known to man.
02 - Fairyfolk traders. When everyone is sleeping fairies switch items and equipment with strange little seeds. What are seeds' magical qualities and why does fairyfolk want to trade those for big people?
03 - Camp of refugees has a problem. Their only water source, the well, has gone bad. Water makes people sick and turn them into centipede each full moon.
04 - Forgotten heir. There is a man in mid 20's claiming to be the real heir but he was outcast for some reason. He has every proof needed (birthmark for example) and he wants to claim his kingdom from his evil brother to rule it wisely.
05 - Raiders trouble countryside not only robbing but pillaging everything. Everyone in the area is terrified and guards and soldiers are powerless. It is rumored that the leader of the raiders is a necromancer and raiders are undead.
06 - Mist of misplace. After characters venture away from the misty area or mist clears they are in unfamiliar location. What strange things are there and how they get back to their own world?
07 - Castle of night. The castle characters are staying is nice but every night people disappear and castle corrupts to ruins of dangers and horrors. People living in the castle don't know about this and live their everyday life perfectly normal.
08 - Genie in the bottle grants three wishes but the prices are horrible. Characters will find this out too late.
09 - Village of orcs ask help because human village's soldiers near-by are killing them just because they are green-skinned.
10 - Through his magical mirror master thief can get everywhere to commit his crimes. Characters are asked to solve the mysterious crime spree.
11 - Characters catch an illness from a plague, but the cure is not easily available.
12 - Traders want characters to guard their trip through dangerous wilderness to a remote city.
13 - Weather goes nuts killing the crops, flooding the village etc. Evil wizard is behind this.
14 - Wizard summoned elder demon and to kill the demon legendary weapon must be crafted from pieces scattered all around the realm.
15 - Orphan child with mysterious powers is found, but a cult wants him/her dead.
16 - Characters are mistaken for someone else. They are treated generously until the day they are meant to sacrifice for gods.
17 - New god is born and wants characters to be his warriors.
18 - Characters loot a statue but every time they try to sell it they find it coming back. They get lots of money but make enemies who claim them to be hustlers. Also the statue has weird unwanted power they find out later.
19 - Character's horses start to talk. It might be funny, but with new intelligence the horses are not anymore that satisfied how characters treat them.
20 - Werewolf attacks characters but manages to escape. Every character in party is now a werewolf with new powers but also with disadvantages, like mark-of-the-wolf what makes people to avoid or want to kill them.
21 - The shrine of unknown god is guarded by living statues. But there is clearly something valuable on top of it.
22 - Suddenly for some strange reason no one can understand player party anymore even though characters understand the people whose language they are familiar with. What is the cause of this?
23 - Mercenaries want help from characters to kill a monster. But the monster is way bigger than expected. As big as a mountain and in a really bad mood.
24 - Ruins of dead soldiers haunting it is a place to go fetch something (item, prisoner). The problem is, that you can't see nor harm the ghost with normal means.
25 - After a big earthquake a crack opens in the middle of town. Hell spawn and other critters come up and the source must be dealt with.
26 - Characters find cursed treasure. No one is willing to buy it and characters cannot just toss it away. It is a burden they must carry unless find a way to break the curse.
27 - Every night mysterious huge moths attack characters. Where do those come from and why are they attracted to the party?
28 - The map shows lost city of gold but it is underwater. Stock up with spells and water breathing potions.
29 - Mutants or other monsters live in the hills near where characters rest the night. Characters are snatched in and kept as prisoners until they are eaten. Unless of course they manage to escape the tunnels infested with mutants.
30 - The city characters are staying is suddenly surrounded by a force field. You can't get over, under or through it. But there must be a way to break it.
31 - Characters switch bodies (swap the character sheets between players). They have new characteristics but personality stays the same.
32 - Strange beam transports characters into a spaceship with weird technology and alien race. They are studied and kept as prisoners. Escaping is only solution, but how to get back on surface?
33 - Everywhere characters go they see this same symbol. On tiles of walls, curtains, clothing of people, tree stumps etc. What do these symbols mean?
34 - Caught in the middle of war. Escaping the scenery would be a suicide.
35 - Mad scientist hires characters to guard his journey with strange flying ship. But the emergency landing in strange jungle/desert/mountains/isle was not in the plan.
36 - City has mechanical clocwork golems for guards and to do everyday labor. But one day golems go mad for a murdering spree.
37 - Characters share same dream in a twisted dream world. But they don't seem to wake up naturally to escape it.
38 - People and other intelligent races are replaced with walking and speaking animals.
39 - Mystical tattoo artist promises characters tattoos with great powers. But the powers have horrible consequences.
40 - There is new glorious tomb being built for old king's corpse. But the problem is that the undead guards don't want king to be moved.
41 - Elven see visions where every other race is destroyed. Do elven keep this as a quiet secret or do they tell about it fearing how other people will think about it. What about elven characters who "know" that their comrades will be destroyed soon?
42 - There is a magic book with really mysterious unknown spell. The spell needs components hard to find. Does character party's magic-user try to solve and cast the spell or does party sell it for someone? Was it a mistake to sell it?
43 - Every morning dead people are found in the streets. Cause of death is unclear but every body has a mark in the forehead. One morning characters wake up with this mark. How to prevent their death the next night?
44 - Every time characters camp they see a mysterious stranger staring at them from distance. When approached he gets away. What does this stranger want?
45 - Characters stumble to a lost valley and cannot be back the way they got into. People living in there are primitive and dinosaurs (or monsters if dinosaurs are normal in the setting) are a danger.
46 - Weird castle with high walls rises near characters. What is the place and where did it come from?
47 - Characters find really realistic statues (from a dungeon, castle, wilderness). They soon realize that the statues cry and are actually real people turned to stone. How to revert this condition?
48 - Characters decide to rest in a nice small village of generous and hospital halflings. But they don't know that these halflings are a tribe of cannibals (well, eating humans, orcs, elven, dwarven, what-not) and plan to eat characters later.
49 - Players are asked to kill a dragon/monster but when they get there, the dragon/monster is harmless and really friendly and generally misjudged as evil.
50 - Skillful adventurers are asked for a playful tournament. But when tournament starts they find out being trapped in a pit. Fight or die!
51 - Characters get really powerful healing potions, but the withdrawal symptoms are horrible and they get immediately addicted.
52 - Looted talking magic sword has his own personality, history and motives. Sword is actually a princess enthralled into a sword by an evil witch.
53 - In the city there is huge problem with rats and insects. They seem to be swarming from sewers in huge numbers.
54 - Characters are lost even though it seems impossible. Now it is all about survival for food and shelter to get back to track.
55 - Characters must destroy a coven of witches half woman half cocroach. But the witches are not evil at all. They are just misunderstood.
56 - In the far north - land of the giants - there is a great treasure an explorer wants to retrieve. He hires characters to accompany him assuring that giants are stupid and easy to avoid...
57 - Travelling characters stumble upon an area of spiders. They are everywhere and their queen is really, really nasty.
58 - The king is young but weak of sickness. He asks characters to find any solution to cure him. But who is behind the sickness and why does he want the young king dead?
59 - Characters are asked to rescue the princess captured in the castle of horrific creatures from other dimensions.
60 - Characters start to get hints that they aren't real but actually heroes of a story in the book a man writes.
61 - Characters find out about a great treasure in far-away land but are told that in the treasure room there is a teleport what transports those who walk through anywhere they please. Easy in and out throwing treasures through a teleport? No. The travel is hard. The guards are dust golems shrugging off most of the attacks. And the treasury is long deserted and ruined by time and teleport is in pieces.
62 - In wilderness characters find a building site but they cannot figure out what is being built. Is it just a mad scientist with his crew building a device of travelling or is it evil scientist building horrible weapon of mass destruction?
63 - One of the characters finds out he is related to a god somehow. It doesn't affect anything else, but an evil kult knows this also and wants to destroy character.
64 - In dangerous area battling monsters characters find out that every time they are wounded the wound grows tiny tentacles. If the tentacles are cut off or healed they grow twice as big back. Explain that to doctor.
65 - In nowhere there is a colossal statue of young man. But in moonlight the colossal statue is animated.
66 - In big city there starts a revolution. People in slums and poor conditions against everyone else. The city gates are sealed and characters are trapped in the dangerous situation. Will they just try to hide, find a solution to solve this politically or take a side in revolution.
67 - Big comet hits the ground blasting a wave of destruction. Everything in that big area known is now destroyed and people must start from the beginning. But from the crater extraterrestial creeps come.
68 - Only characters know that king is not really what he seems to be. Real king is dead and the fake king is a demon from another plane.
69 - When traveling in rain some diamonds fall down. They look normal valuable easy treasures, but when kept in dark (backpack, pouch), they grow into small razor sharp diamond insects multiplying fast.
70 - Death is bored and spots characters. He wants to play a game. Death versus characters in a chess (or other game). If Death wins, he claims characters' souls. If characters win, Death grants one wish possible in his power.
71 - Traveling characters find badly wounded person. This person tells a wild story of war in other planes between lesser gods. And he lost and dropped down here. Now this person who claims to be lesser god wants characters' protection for great prize until he can claim his power back.
72 - Traveling characters stumble upon a huge orc (barbarian, monster) army with at least 10.000 units. Fortunately they didn't spot characters (yet). The army is clearly traveling towards major and important city nearby.
73 - A writer wants to company characters in their adventures to write great books of wonderful stories. But the writer has other plans in mind and the writing process is just a scam to get where/what he wants.
74 - Great treasure is promised to one who will venture into the old catacombs under the city and kill the lich king planning to claim the city above as his undead city killing and necromancing everyone living there.
75 - Zombies have feelings too. In catacombs/dungeons characters encounter lots of zombies. They might not be dangerous but are attacking without hesitation characters. The problem is that the souls of zombies speak with their mouths pleading characters not to destroy their bodies. They cry, wail and scream in pain when hit.
76 - A scout returns the town yelling that huge (I mean HUGE) snake is slowly approaching the city. The snake is so huge it will crush or swallow the city whole.
77 - Characters are captured by experimental scientist who performs strange experiments on them before characters can escape and fight their ways out. Meet mutant heroes!
78 - Characters are asked to help free the real prince from castle dungeons. But there is another replacement prince already - a doppelgänger. Final fight with both real and double prince will be trouble. Which one is which?
79 - There is a prophecy telling that when stars are right [add something really terrifying] happens. And astrologists tell that the stars are about to be right.
80 - There is a legendary place with legendary weapons (one for each character what suits them well; spell book or robe for M-U, armor or weapon for warrior etc.). But to get them is a legendary adventure.
81 - With thunder there comes a horrible avatar of lightning. It teleports to new spot of lightning strike. As avatar is pure energy it is horrible opponents. If it is destroyed it returns the next thunder. And now it is a season of storms...
82 - Everywhere in the area plants are dying including those meant for food. The source is a monument that radiates old evil.
83 - Robbed and stripped. In their camp characters wake up stripped and robbed without any equipment. They were enchanted into a deep sleep. Luckily they can track their robbers but it will be hard to reclaim their possessions without anything. Stealth and cunning is the way to deal with this.
84 - Instead of bards singing about characters' great adventures they sing insulting humor songs what aren't true about characters. How to correct this because the songs are really popular and widespread.
85 - City wants help from the character because all the children are missing.
86 - Characters get an opportunity to build a fortress/castle/tavern/what-not but there is great responsibility and lots of trouble maintaining it. But it can also be really rewarding.
87 - The inn character find is deserted. But there are marks that people have disappeared just moments ago. Plates full of warm food, wine barrel running wine on the floor, fireplace burning etc. Where did the people inside disappear?
88 - Characters run into quick sand/swamp and cannot get free! But when they are sucked in they drop into large cave and must find their way out. What dangers and rewards are there?
89 - Characters find a nice little box. When opened there is a crystal what shows light in one direction no matter which way you hold it. Where does the crystal point and why?
90 - Characters find a piece of paper but it is clearly torn apart. The message seems important/rewarding so they must collect the other parts. Behind each paper is a hint of whereabouts for the next one.
91 - Talking immortal cat accompanies characters and demands them to help him. The talking cat is a talking cat (not a transformed princess or anything) but he will lie if necessary just to get characters to help him.
92 - Everyone in the city/town/area is under a parasite of parasite god. They share mind and if one sees characters others in the area will see them also. The parasite god wants to do his [what ever] without disturbance thus wants to destroy characters. Only way to escape parasitic people is to destroy the parasite god.
93 - Someone from one character's family needs help really bad (not for characters who generally hate their family on are of "unknown past". But the actual problem family needs help to deal with is way worse than they could ever imagine.
94 - Characters find a weird storytelling game where they must create characters. Winning the game grants a prize. (Roleplaying game characters are playing a roleplaying game in a roleplaying game).
95 - One piece from king's chess set is missing and king hires characters to find it. But it is not only a missing piece because there is evil purpose why it is missing.
96 - Evil wizard shrinks characters and puts them into a maze with insects size of horse and rats size of dragons. They must clear the maze and survive. Evil wizard does this purely for entertainment but rewards surviving characters because he had so much fun.
97 - When killed the evil wizard characters had quest to kill he curses them as final words. The curse drops characters' heads off. Now the characters are headless and must carry their heads around finding a way to restore their heads back in the body.
98 - Characters encounter a moving city. City is like small island on mechanical walking feet. People there are nice and invite characters in. The moving city and people living in it are in a quest for [something] and will appreciate characters' help and experience.
99 - When traveling nice lord asks characters to take shelter in his mansion. But the lord is a vampire and either wants characters to join his undead legion by will or force. Be undead soldier for vampire lord or escape.
00 - Characters are transformed to 10-year old kids. Armors and such are too big to wear and weapons clumsy to wield and equipment possibly too heavy to carry around. No one will take characters seriously being really adults but treat them as kids.