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 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.
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.
ClimaxBloody Battle
This is the best Climax for an adventure involving the clash of mighty armies -- or for any adventure where, toward the end, the Master Villain and a large body of minions confront the heroes and their own troops. This finale is characterized by a monstrous clash between the two forces, with the heroes chewing through the enemy ranks to get at the Master Villain and his elite guards. It's strenuous, exciting, and classically simple.
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 ICatacombs
These can be catacombs beneath a living city or a ruined one; they can be long-forgotten or still in use.
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 VillainSufferer
This Master Villain disguises himself as some other sort of villain. Long ago, he was given an ugly curse -- he longs for death but can never die unless slain by heroes unaware of his curse. (Naturally, the way the curse works, he has to defend himself when attacked by the heroes.) So this villain works hard to make sure the best heroes in the world have sufficient cause to want to come and kill him. He'll insult them, ruin them, kidnap or murder their loved ones, whatever it takes to bring them against him. Often, he can only die -- his curse can only be undone -- in one specific holy place, so he'll have to lure the heroes to that place to face him. If the heroes are doing research on the villain all this time, they may find out his secret, leading to a sad and painful end to the episode as the unkillable villain has to leave and find someone new to kill him.
Minor Villain IMoronic Muscleman
This fellow is a huge, powerful monster of a fighter. His job is to smash anything the villain tells him to smash. He does that very well, but don't ask him to do any thinking; he has no time for such brainy stuff.
Minor Villain IIChildhood Friend with a Dark Secret
This Minor Villain is like the character of the same name from the Allies and Neutrals section. However, the heroes find out early on that he's really working for the Master Villain. He may not wish to be helping the villains; his family may be held hostage, or he may just be too frightened of the villain or otherwise weak-willed to refuse. Alternatively, he could actually be evil now.
Ally/NeutralObsequious Merchant
This fellow is the owner of the caravan the heroes are protecting, or the merchant the heroes encounter when they desperately need to buy something. He is oily, ever-flattering, overly agreeable, and is a sharp bargainer; the heroes will not find him willing to give them a sale price.
Monster EncounterKing Beast
At some point in their adventure, the heroes run across a King Beast -- some enormous, intelligent monster (which speaks the Common tongue) which is the leader of its species. Perhaps it needs help; if the heroes help it they'll earn themselves a favor which the King Beast will repay at some later time in the adventure. Perhaps the heroes are in deadly danger and need help; the King Beast can be persuaded to help, but only in return for a deed or favor in the future.
Character EncounterBlackmailer
If the party is pulling a scam, this person knows it and can tell the potential victim; if they're wanted by the authorities, he's willing to alert the authorities that they're here; if they're hiding out from the Master Villain, he's going to tell said villain that they're here; he may have kidnapped one of their favorite NPCs and be holding him for ransom; and so on.
DeathtrapColiseum
If it's appropriate, you can have the heroes captured by the local authorities -- particularly when they're in an exotic land, lost world, or whatever -- and have them armed with gladiatorial gear and dropped into a coliseum for the entertainment of the locals. (Note that this works much better with fighting-type heroes than spellcasters.)
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 ConditionMagic Doesn't Work Right
If the adventure is taking place on an alternate plane, then that plane's magic works oddly or not at all. (A spellcaster will find that just making himself useful is a challenge when none of his spells works.)
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 HerringLying Rumor
This is the worst and most useful type of red herring -- the interesting rumor which just happens to be false. In adventures of this sort, the best Lying Rumor concerns the Master Villain; it gives the heroes some "important" information about him which later turns out to be useless.
Cruel TrickVillain is Related to Hero
In this very irritating complication, one of the heroes discovers that the Master Villain is related to him. The villain might be his long-lost father or twin; perhaps this relative is not long-lost after all, but has secretly been a Master Villain for years, and only now has the hero discovered it.

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