Random Adventure Generator

ThemeAction/Adventure
This is the most common and straightforward sort of adventure there is. In the Action/Adventure scenario, you present your characters with a task and then confront them with obstacles to overcome in order to accomplish the task successfully.
GoalExplore a New Area
The heroes are hired or convinced to enter an unmapped area and explore it. They may be making a map; they may be trying to find someone who disappeared into this area in the past; they may be following legends that tell of treasure in the unexplored interior.
Story HookMissing Memories
One or more of the PCs wakes up with no memory of the recent past, and now they find themselves in some kind of trouble they don't understand. The PCs must find the reason for the memory lapse, and solve any problems they uncover in the meantime.
PlotA-B-C Quest
This is an epic sort of plot. In it, the heros are given (or undertake) a task to perform: The taking of a city, the rescue of an innocent, the destruction of a monster, the creation of a magical item, the defeat of a Master Villain, etc. But the path to victory is not a simple one. To get to their goal, Event A, they find that they must first accomplish some other task -- Event B. But when they undertake the task of accomplishing Event B, they find that they must first accomplish Event C. This goes on for several encounters, until the heroes accomplish all the obstacle events which prevent them from returning to Event A, their original goal.
ClimaxThrone Room Duel
This is set up much like the Scattered Duels, except that you don't separate the heroes. It's harder to control whom fights who in this situation... but if it doesn't matter who has the final duel with the Master Villain, this is a classic climax choice.
General SettingCosmopolitan City
Most of the story takes place in a large, sophisticated city; center the villain's plot and activities around that city. This setting is best suited to adventures involving more people than monsters; most of your villains should be human or demi-human.
Specific Setting IMilitary Encampment
This is best used in an episode involving warfare; it could be the good-guy army's encampment, from which the heroes launch their adventures, or the villains' encampment, in which case the heroes might have to sneak in on a mission or escape from it if they're captured.
Specific Setting IIMansion of a Lord
This can be the home of a villain -- the characters may have to break in and rescue someone or steal evidence, or break out if they've been captured -- or of a heroic ally, in which case it may be used as the headquarters for the heroes' plans and activities.
Master VillainCorruptor
The Corruptor is the villain who wants to make something nasty out of something that is currently nice. He may be working on a small scale -- i.e., wish to corrupt one character or a few characters, particularly PCs and their favorite NPCs. Alternatively, he may be a big-scale villain trying to change an entire city or nation into a jaded, debased pit of sin, hatred and death.
Minor Villain IMistress with a Heart of Gold
This character is much like the "Lover or Daughter of Villain" type of Mystery Woman from the Story Hooks section. In this case, she usually accompanies the Master Villain, but sometimes goes on missions of her own, where she runs into and develops affection for one of the player-characters.
Minor Villain IIMistress with a Heart of Gold
This character is much like the "Lover or Daughter of Villain" type of Mystery Woman from the Story Hooks section. In this case, she usually accompanies the Master Villain, but sometimes goes on missions of her own, where she runs into and develops affection for one of the player-characters.
Ally/NeutralTragic Fellow Hero
The heroes are in the company of some hero well-known to them; he may have been a companion or ally, or they may just know him by reputation. He is a tragic figure; he may have lost his family to the master villain, or lost his properties and titles, or be afflicted with a curse he cannot be rid of, or be committed to a quest he knows will take his life. He's dour, and gloomy, prophesying doom and having no fun at all.
Monster EncounterReconaissance Monster
At some point in the adventure, the Master Villain will become aware of the heroes' activities against him. If he has magical abilities or a magical servant, he will send some sort of quiet, clever monster to spy on the heroes. The heroes should have an opportunity to realize they're being spied upon, leading them to a mad scrable as they try to capture or destroy the spy.
Character EncounterInquisitive Official
Some local authority has noticed the characters' presence and it makes her curious. She snoops around asking questions all the time. She may be a city guardsman or special agent of the ruler, but (functionally) she's a police lieutenant, asking the rong questions at the wrong time; the heroes have to work around her, sneaking where normally they'd be able to work in the open.
DeathtrapAnimal Pit
This is a classic trap of the adventure genre: The heroes (perhaps just one hero) are dropped into a pit filled with dangerous animals -- snakes, lions, bears, whatever. They must either fight the beasts or delay them until they can escape -- climb back out, open a secret door, break down a wall, have a rope lowered by friends above, etc.
ChaseFootrace
The chase involves the characters on foot, probably through such terrain as city streets or the corridors of a palace. One hero may realize that the's being pursued by a party of enemies and choose to run for it; the heroes may have caught up to the Master Villain, prompting him to run for his life.
Omen/ProphesyInnocent Fulfills Prophecy
An innocent could fulfill a prophecy -- one which endangers his/her life. This innocent might, for instance, be the one who is supposed to slay the king, but is not a mighty adventurer able to protect himself from the king; the heroes may find themselves sheltering and helping this poor dupe.
Secret WeaknessElement
The Master Villain can be banished, dispelled, killed, or otherwise defeated by some of element or item. The Master Villain tries to get rid of all the examples of this element in his vicinity; he doesn't let his minions carry it or bring it into his presence. But he's not stupid; he doesn't announce to the world what his weakness is. He tries to hide his concern within another command. If he's allergic to red roses, for instance, he orders all "things of beauty" destroyed within miles of his abode.
Special ConditionTime Limit
Finally, the most obvious condition to place on an adventure is to give it a time limit. If the Master Villain is going to conclude his evil spell in only three days, and his citadel is three hard days' riding away, then the heroes are going to be on the go all throughout the adventure -- with little time to rest, plan, gather allies, or anything except get to where they're going.
Moral QuandryHonor Quandry
You want to use this on the character with the most strongly developed sense of personal honor -- someone who has lived all his life by a strict code. Toward the end of the adventure, this character realizes that the best way to defeat the Master Villain is a violation of that code. For instance, the character might be a paladin, who discovers that the only possible way for the heroes to defeat the Master Villain is to sneak up on him and stab him in the back.
Red HerringFalse Path to the Artifact
Once again, if the heroes have had too easy a time finding the artifact capable of destroying the villain, give them trouble this way: When they get to the place where the artifact is supposed to be contained, they find the coffer or chamber or whatever empty, obviously looted by robbers, who have scrawled such remarks as "Kelrog was here!" upon the walls.
Cruel TrickVillain Accompanies Party
In this distressing situation, the Master Villain, in disguise or his secret identity, accompanies the heroes for much of their quest. He gets to know them, learns their strengths and weaknesses, learns their plans, and just as soon as it's most efficient for him, he thwarts their current plans and leaves. Alternatively, the Master Villain might be with the heroes all along, up to the very end; the heroes know that one of their companions is the villain, and the whole thrust of the story is finding out who he is. This is the whole purpose of most Mystery-type adventures.

Based upon tables from the Dungeon Master's Design Kit by TSR, Inc.