Random Adventure Generator

ThemeRomance
This sort of adventure (rarely played, but worthwhile anyway) has as its central plot the romance between two characters, usually a player-character and an NPC.
GoalClear Name
The name of one of the characters or an NPC has been sullied and the characters must clear it. The characters must find out a) why the name has been smeared, b) who is responsible, and c) why the responsible party is doing it; then they must find evidence to convince everyone they're telling the truth.
Story HookDying Delivery
On some occassion when the hero is out wandering the streets or is otherwise all alone, a dying man bumbs into him, hands him something, says a few words, and dies.
PlotGeographic Progression
This is the simplest sort of adventure plot. The heroes have an area to investigate or travel through; they have encounters based on where they are. For instance, the traditional dungeon, where monsters are tied to specific rooms or areas. Or, if the heroes are travelling along a narrow valley or through an enchanted forest, they might suffer ambushes and other encounters fixed to various points along their travel plan. The plot, then, is getting to the villain by surviving the intervening obstacle encounters.
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 Road
Most of the adventure takes place on the road, as the heroes are travelling from place to place. This is especially good for adventures where heroes are investigating a wide-ranging mystery, are part of a caravan, or are being pursued by loathesome villains.
Specific Setting ITavern/Inn
This is a classic fantasy setting, the residence of travelling heroes and the home of the tavern brawl.
Specific Setting IILost City
This is the remnant of some lost civilization or expedition, still thriving in some forgotten corner of the world. Remnants of lost civilizations can even inhabit cavern systems beneath campaign cities, preying on the above-worlders for their goods, slaves, and sacrifices.
Master VillainZealot
This villain is like the Conqueror, but he's not trying to conquer to own; he's trying to purge the world of something he feels is pure evil (another religion, a human, demi-human, or nonhuman race of sentient beings, a custom). He operates just like the Conqueror, enslaving or killing all those who belong to the "wrong" race or philosophy.
Minor Villain IInquisitor
This villain is the one who interrogates the heroes and NPCs captured by the villains. He accompanies the other Minor Villain out into the field and works on anyone captured; he enjoys inflicting pain and suffering.
Minor Villain IICoward
This character is an ordinary grunt minion of the Master Villain, but he's a coward. He's deathly afraid of the Villain and the heroes. He's best used when you plan to have the heroes captured; by his mannerisms, you can make it clear to them that this fellow is a coward and they will begin to work on him psychologically.
Ally/NeutralAbsent-Minded Expert
The characters find they need an expert in some fields -- pottery, alchemy, whatever -- but all they can find is a somewhat daffy and absent-minded master of that subject. He's useful when around his subject matter, but otherwise absent-minded, incautions, in frequent need of rescuing, etc.
Monster EncounterNocturnal Predator
This is a classic monster encounter; the arrival of a hungry carnivore in the middle of the night. Usually, this attack happens to heroes camping between villages or out in the deep wilderness; a wild animal, attracted by food odors (from the heroes' campfire or from the heroes themselves) sneaks in for a bite.
Character EncounterNew Enemy
In the course of his ordinary activies, one of the heroes can make a New Enemy. Hurrying along the street, he can bump into a disagreeable fighter for whom an apology isn't enough; in a tavern, he can make some innocuous remark that you deliberately have the irritable fellow misconstrue as an insult. The New Enemy will only exchange heated words with the hero at this point, but will appear again later in the adventure and will eventually have to fight the hero.
DeathtrapPit and the Pendulum
Actually, we're applying this term to any of many time-delay deathtraps. In this sort of trap, the villains capture the heroes and place them in a trap which will soon kill them -- it operates on a delay, often based on a timing device or a burning fuse.
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/ProphesyHero Fulfills Prophecy
This is the most useful sort of prophecy. In the early part of the adventure, one of the heroes discovers that he fulfills some ancient prophecy.
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 QuandrySaving Quandry
Finally, another classic quandry puts the heroes in the position of choosing between a grand opportunity to hurt the Master Villain -- or saving the lives of a number of individuals.
Red HerringArtifact that Doesn't Work
Often, epic quests against powerful Master Villains require that the heroes find some legendary artifact, the only object which can defeat the villain. If your heroes have had no trouble getting to the artifact -- they've effortlessly sliced through every obstacle you've put in their path and are confidently advancing on the resting place of the magical item -- you can have it not work.
Cruel TrickNPC Turns Traitor
He may alert he enemy when the heroes are planning a raid; he may steal the artifact and take it to the villain; he may stab a hero or important NPC in the back (literally) before departing.

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