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.
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 HookGrim Necessity
If the hero doesn't involve himself with this adventure, he's going to find himself suffering or dead -- period. That's the hook to bring him into the adventure... but you have to determine why he'll suffer or die if he doesn't become involved.
PlotSeries of Villains
This is a very dramatic plot, and very well-suited to oriental campaigns. In it, the heroes have undertaken a quest, usually the finding and defeat of the Master Villain. They may have to travel to his citadel, or head off in another direction to find some artifact capable of defeating him, or run away from pursuing villains until they can figure out what's going on. All along their route, they are set upon by villains -- each villain has a name and distinct personality, and each encounter is life-or-death for the heroes and villains; the villain never escapes to safety if the tide turns against him, he fights unto death.
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 SettingHero's Home Town
The action takes the heroes back to the home territory of one of them. Note that this usually means that this hero's family or old friends are deeply involved in the adventure.
Specific Setting ICaves of Magical Folk
These can be either beautiful, glittering homes of gorgeous magical peoples, or the dank and terrifying lairs of horrible monsters.
Specific Setting IICatacombs
These can be catacombs beneath a living city or a ruined one; they can be long-forgotten or still in use.
Master VillainOrganizer
This Master Villain is the head of the local criminal syndicate -- the Thieve's Guild or slaver ring, for instance. He's cold-hearted and unsympathetic, and human life means nothing to him. He employs assassins and musclemen against the heroes, and can only be reasoned with when it's going to profit him more to cooperate with the heroes than kill them.
Minor Villain ICoward
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.
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/NeutralMerry Minstrel
This character follows the heroes in order that he might find inspiration for his song and storytelling. He can't be shut up; he sings all the day long and into the night, is a showoff before crowds, and is far too noisy for a party trying to remain unobserved.
Monster EncounterRavager
This is another classic monster encounter; the monster which is bedeviling a community or local area and will continue to do so unless the heroes destroy or defeat it. Yes, this is similar to the Master Villain of the same name, but the Ravager usually has no master plan -- it just wants to kill, destroy, or eat.
Character EncounterMean Drunk
The Mean Drunk works much like the Belligerent Soldier except that he's not as tough, is of course drunk, and is usually accompanied by other Mean Drunks.
DeathtrapStampede
Should the heroes ever cross plains or prairies, their villainous enemies may wish to stampede a herd of large animals at them. Alternatively, beasts in the forest may be stampeded by fires set by the villains; in this case, it will not be one sort of animal charging through, but a mixture of terrified forest animals, from the smallest fox-cub to the largest bear.
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/ProphesyFortune Teller Predicts Doom
This is an ominous encounter: A fortune-teller predicts doom for one of the heroes, or for some community menaced by the Master Villain. Shortly after, some calamity should befall the hero: He can be attacked by an assassin, be in a building when it is struck by fire or an earthquake, or suffer other danger. Investigation of the events can then point the heroes toward the Master Villain as the event's instigator.
Secret WeaknessSecret Embarrassment
Finally, the villain may have some aberration or secret shame that will force him to flee when he is confronted with it. It could be something as simple as the fact that his nose is too big, or that he is a small and nebbishly wizard pretending to be some vast, powerful demonic power. When his shame is revealed, he is too humiliated to continue; this is a good option for comedy adventures.
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 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 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.