Random Adventure Generator

ThemeHorror
This type of adventure is designed to scare both the characters and the players. Just having a monster attack is not enough for a horror theme; the monster must first frighten the characters.
GoalWin War
In this adventure or set of adventures, the characters become part of an army -- a force assaulting another kingdom, perhaps, or an army defending one realm from another.
Story HookMystery Woman
Create an NPC "mystery woman" sure to be fascinating to your hero and have her keep appearing inexplicably in his life. As he becomes interested and investigates her, he keeps stumbling across the villain's plans and becomes inextricably mired in the plot. (For female player-characters, the Mystery Man is just as useful.)
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.
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 ILost 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.
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 VillainConqueror
This character is moving his army in to take over; that's what he lives for. He's been the enemy of your characters' nation's ruler, and has launched a full-scale invasion of your characters' favorite nation. The heroes have to beat their way through or elude his hordes of soldiers in order to get at him; better yet, they might lead their own nation's troops against his and outthink him in military fashion.
Minor Villain IChief 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.
Minor Villain IIHard-Eyed Advisor
This is the sort of villain whom the heroes see in the Master Villain's throne room. He's hard-eyed and scary; life means nothing to him and he enjoys killing. He's also a good advisor to his master.
Ally/NeutralRomantic Loony
Somewhere, the heroes bump into a lunatic who falls immediately in love with a player-character and won't leave him or her alone. This character may be a love-smitten village lass or nebbishy adventurer. Whatever the origin, this character must be hopelessly in love with the character but have some trait which keeps the character from reciprocating; perhaps the loony is too plain, too crazed, or too stupid. Whatever, he or she really is sincere in his affection for the character.
Monster EncounterAssassin Monster
This mosnter, at some time in the adventure, is sent by the Master Villain to attack one or more heroes when they're at their most vulnerable -- asleep, enjoying themselves, etc. Usually, the Assassin Monster attacks, but the hero, though injured, is able to hold it off long enough for his friends to respond to his shouts. The Assassin Monster is usually killed by his friends, who can then speculate on who sent it and why.
Character EncounterThief
At some point in their adventure, the heroes have a run-in with thieves.
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.
ChaseSpecial Terrain
You can make any chase more memorable by having it take place in a setting to which it is utterly unsuited. For instance, horse chases are fine and dramatic when they take place through the forest, out in the open plains, or along a road -- but they become diabolical when they take place inside the Royal Palace or in dangerous, labrynthine, treacherous catacombs.
Omen/ProphesyTotem Animal
If a hero has an animal which is his totem, he may see the animal engaged in a fight to the death with another animal -- one which, coincidentally, is the totem of one of the villains. How his totem defeats the other -- or is defeated by it -- gives the hero some clues as how to fight his actual opponent when the time comes.
Secret WeaknessLack of Familiarity
The Master Villain, if he comes from the past or another dimension, or belongs to an alien race, might be sufficiently unfamiliar with this world that he essentially defeats himself. How? By making incorrect guesses about human behaviour. One classic error involves underestimating the human capacity for self-sacrifice.
Special ConditionOmnipresent Observer
If a wizard, demigod or god has forced the heroes to undertake this quest, he may be with them continually -- in spirit. He can't help them, but does magically watch everything they do. And when they do something he doesn't like, he tells them about it -- loudly and nastily. (This is distressing when they're trying to break into a fortress or sneak through enemy lines.)
Moral QuandryAlly Quandry
You set up the situation so that the heroes have a good chance at defeating the Master Villain if they get the aid of two specific individuals, probably experts in fields relating to the villains' activities. But the two experts hate one another and refuse to work together, even if it costs them their world.
Red HerringExtraneous Details
When giving the heroes details on their enemy -- for instance, details they are learning from investigations and readings -- you can give them just a few details too many. This may prompt the heroes to investigate the "extra" (i.e., irrelevant) details in addition to the relevant onces, thus losing them valuable time.
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.