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.
GoalExplore a New Area
The heroes are hired or convinced to enter an unmapped area and explore it. They may be making a map; they may be trying to find someone who disappeared into this area in the past; they may be following legends that tell of treasure in the unexplored interior.
Story HookOld Friend
Another classic story hook is the Old Friend, the childhood friend of our hero, who shows up in one of several ways to drag the hero into the story.
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.
ClimaxDivine Retribution
Here, the heroes' goal has been to alert the gods that the Master Villain threatens them or their plans; in the last scenes of the adventure, as our heroes face an overwhelming enemy force, the gods bring down their divine retribution on the villain, causing a massive earthquake, tidal wave, lightning storm, or flood of monsters. This is all well and good, but the heroes are too close and must escape the fringe effects of this awesome disaster. A variant on this is the Natural Disaster. No gods are actually involved, but the Master Villain has been tampering with the delicate forces of nature. He may, for instance, have been powering his master spell with the energies of a volcano. When the heroes attack the scene of his spellcasting, the spell goes out of control and so does the volcano. The villain is consumed in the eruption and the heroes must escape or be consumed themselves.
General SettingOn the Sea
Most of the action occurs on the sea -- the heroes are shipborne for some reason, docking in lots of ports. Again, this is good for adventures where the heroes are investigating clues left all over the map, are part of some trading enterprise, or are being pursued by villains.
Specific Setting IShacktown 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.
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 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 IMisguided Moralist
This fellow has been convinced that only by helping the villain achieve the Master Plan can he improve the world. He tends to be encountered all through the adventure's plot, usually escaping from the heroes and taunting them for their wrong thinking. Fortunately, he's no more effective as a villain than he is as a thinker.
Minor Villain IISingle-Minded Soldier
This most trustworthy of villain minions is the experienced, competent, persistent soldier -- a field-trained officer who serves the villain with military precision. He is usually encountered in the field as leader of the villain's field operations. He is not encountered directly until the middle of or the latter part of the adventure; until then, the heroes encounter only his subordinates.
Ally/NeutralGrumpy Old Professional
Again, the heroes need an expert in a certain field -- this time a craft or art, such as blacksmithing, engineering, horse-training, or whatever. The only or best professional they can find is an aged expert. He's grumpy, cranky, and sharp-tongued; he constantly complains about the food, the weather, his companions, the decline in skill of his co-workers since he was a young man, the road conditions, the rotten pay he's receiving, and so on.
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 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.
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.
ChaseEndurance
The Endurance Chase is not some sort of climactic chase -- it's a rugged, tiring, persistent pursuit that tests the characters to their limits. In this chase, the heroes and villains are pursuing one another across a lot of territory and they're not catching up with one another very fast. This may be a horseback pursuit across a hundred miles of savannah, a camel chase across several days' worth of desert, or a chase across arctic tundra.
Omen/ProphesyComet's Progress
Events during the adventure may be enlivened by a large and menacing comet which appears in the night sky for several days during the scenario; the locals take it for an omen of doom. The comet may be the result of magic being used by the Master Villain, or the comet's appearance can pertain to an old legend involving the Master Villain.
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 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 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.