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.
GoalProtect Endangered NPC(s)
One or more NPCs are in danger, and the characters must protect them. They might be doing this for a reward, or because one or more of the NPCs is a friend or relative of the character. You need to decide what the characters are protecting the NPCs from. The NPC might be a wealthy or powerful person being sought by assassins or kidnappers. The NPC might be a whole village of peasants who are being terrorized by a bandit chieftan.
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.
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 SettingExotic Distant Land
The adventure will take the heroes to some fascinating and exotic distant country, where they'll have to cope with new customs, monsters unfamiliar to them, and very colorful NPC encounters; choose one of the more fascinating foreign lands from your campaign world.
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 IICaves of Magical Folk
These can be either beautiful, glittering homes of gorgeous magical peoples, or the dank and terrifying lairs of horrible monsters.
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 IAvenger
This character is much like the Master Villain of the same name, but he's not in charge of all this villainy, and he's definitely an enemy of one of the player-characters. You'll have to decide who he is and why he hates one of the heroes; he could be anything from a recurring villain to someone who simply lost a fight to the hero once.
Minor Villain IIInquisitor
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.
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 EncounterTerrain Monster
Don't forget the simple run-in with the animal belonging to the terrain where the heroes are: Every type of wilderness has its predators and big, nasty herbivores.
Character EncounterOld Friend at the Wrong Time
When the heroes are trying to sneak through a guardpost, citadel, or city where they can't afford to be recognized, one of the characters' old friends recognizes him and loudly renews their acquaintance in full view of the guards looking for the characters. This usually leads to an exciting chase as the heroes must escape.
DeathtrapDemolition Zone
In this classic deathtrap, the heroes are placed (usually bound and weaponless) in some building or area just as it's due to be destroyed.
ChaseHorseback
This is a relatively short chase -- it only needs to go on for a mile or so before even the best horses are winded. If it goes on longer than that, the horses may collapse and perhaps die.
Omen/ProphesyBirthmark
One of the heroes has a birthmark that pertains to the adventure in some way. He may have a birthmark identical to some NPC -- for instance, some person endangered by the Master Villain. This mystery can give the hero his reason to become involved. Alternatively, his birthmark may mark him as a hero fulfilling some ancient prophecy.
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 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 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.