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.
GoalRetrieve Item
This goal is like the Rescue, except the victim is an inanimate object. This item may be an artifact, a paper containing evidence against a character or patron, an antidote needed to save another NPC or palyer character, or just some item of sentimental value -- an item which one NPC hires the characters to steal from another NPC.
Story HookOld Enemy
This is a straightforward story hook; the hero learns that his oldest enemy is back and is very active in the campaign, up to something. The hero will naturally want to investigate and will walk right into the story.
PlotEvent
For this plot, choose some sort of event -- a tournament, a holiday, a celebration called by the king, a masked ball, or whatever -- and set the commencement of the Master Villain's plan against that backdrop.
ClimaxPrevented Deed
Here, the heroes have been defeated -- captured by the Master Villain, or so thoroughly cut up by his minions that all believe them to be dead. And the heroes have learned, from the bragging of the villain, loose talk of his minions, or examination of clues, what is the crucial event of his master plan. In any case, the battered and bruised heroes must race to this site and have their final confrontation with the villain, bursting in on him and his minions just as the knife or final word or key is poised, and prevent the awful deed from taking place -- and, incidentally, defeat the master villain and minions who beat them previously.
General SettingOn the Sea
Most of the action occurs on the sea -- the heroes are shipborne for some reason, docking in lots of ports. Again, this is good for adventures where the heroes are investigating clues left all over the map, are part of some trading enterprise, or are being pursued by villains.
Specific Setting IClassic Dungeon
This would be the standard monster-filled labyrinth; perhaps it's a nesting ground for the master villain's monster troops.
Specific Setting IIShacktown of the Oppressed
Part of the action centers around the tenements or shacks of the worst part of town; perhaps an allied NPC lives here or the characters are fugitives hiding out in the nasty part of town.
Master VillainAdvance Agent
This villain is the vanguard of some sort of invastion; often, he is trying to open up a portal to a dimension full of trapped demons and evil gods.
Minor Villain ISingle-Minded Soldier
This most trustworthy of villain minions is the experienced, competent, persistent soldier -- a field-trained officer who serves the villain with military precision. He is usually encountered in the field as leader of the villain's field operations. He is not encountered directly until the middle of or the latter part of the adventure; until then, the heroes encounter only his subordinates.
Minor Villain IIChief Assassin
The Chief Assassin is the favorite killer of the Master Villain. The Assassin works mostly in the field, first killing witnesses who might prove harmful to his master, then zeroing in on the player-characters. He usually meets his end before the adventure's climax, but he may taken one of the heroes down with him.
Ally/NeutralHero Worshipper
Some youth -- an urchin, a brother or sister of one of the heroes, or a child run away from home -- hooks up with the heroes, following them wherever they go, being admiring, talking to everyone (neutrals and villains included) about how wonderful and powerful the heroes are.
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 EncounterLying Accuser
A captured thief may accuse the character of putting him up to the theft; an abandoned mother may accuse the hero of fathering the child; a reputable witness (working for the Master Villain) may accuse the hero of a murder or robbery. The hero shouldn't know what he's accused of until he's hauled in by the authorities.
DeathtrapRock and a Hard Place
This trap starts out as an Animal Pit, Pit and the Pendulum, or Tomb Deathtrap, but an obvious escape suggests itself very early on. Trouble is, it leads into even worse danger. The hole out of the animal pit may lead to the lair of an even worse animal; it may lead through a succession of dangers (collapsing old catacombs, into an underground river, into a den of zombies) before the heroes reach the light.
ChaseAerial
The heroes could be riding pegasi or friendly griffons or allied great eagles; the villains could be carried aloft by gargoyles or demons. The prospect of taking a mile-long fall if one's mount is hit is a very daunting and challenging one for the hero.
Omen/ProphesyReincarnation
The hero, seeing the portrait of some long-dead nobleman, may be surprised to see his own face staring back at him. All evidence points to the fact that our hero is the reincarnation of this person, and the Master Villain may desire to destroy any trace of that nobleman's existence. Just as appropriately, this long-dead nobleman may have died after making some important choice -- such as choosing love over career or career over friends; and the choice he faced is identical to the one the hero now faces. Will our hero defy the prophecy and choose as he did in a previous life, or will he choose the other option and see what happens?
Secret WeaknessLove
The Master Villain possesses the "weakness" of genuine affection or love -- probably for some NPC, though it could be very intriguing if the object of his affections is a player-character. The heroes can then defeat the villain by holding his loved one hostage, or proving that his loved one will be seriously harmed, betrayed, or killed if the villain keeps up with his activity.
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 QuandryFriend Quandry
At a critical point in the story, one of the campaign's NPCs makes an impossible demand of one of the heroes.
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 TrickWanted by the Law
One final complication, one which occurs pretty frequently, is when the heroes are wanted by the law. When they're wanted by the law, they have to travel in secret and very limited in the resources they can acquire.

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