I've seen threads out there challenging folks to craft a world w/only 5 random PC races dominant, low-level sword designs and random wondrous items. Here's one more to try (though lets be honest: I doubt I'll get much traction).
Craft an adventure around a single, random detail
Recently a buddy said he was strapped for ideas. He's running in Forgotten Realms. I took a look at the Sword Coast and one detail stuck out to me: Paladins. They guard the Trade Way but it doesn't go into detail for what religions/orders and such.
Paladins...Paladins; it just stuck in my head. So I wrote the word down and brainstormed. In a few hours I had a megadungeon called Flamenwing Castle where a paladin/sorcerer built an order dedicated to protection and the dragon-deity Bahamut. This attracted a blue dragon, her kobold minions and her impressive storm magics. Now the ruin is plagued by Dragon Squalls, the dungeons below have kobolds (among other things) but approach TO the dungeon is guarded by the paladin's order, which includes bizarre, Brass-skinned kobolds (the paladin/sorcerer had a brass dragon bloodline).
So take a random detail, like a particular monster, a singular trap or device, or perhaps a single aspect of setting. The more specific the better. Challenge yourself to craft some kind of adventure and deposit your impetus and synopsis here.
....Traps.....Traps.....Stone block trap?
Okay. Megadungeon. There is a singular Stone Block Trap which triggers through every single floor before reappearing at the very top of the dungeon. Countless adventurers have attempted to plunder the treasures of this eccentric trapsmith's lair but none have succeeded! Upon reaching the very bottom floor and hopefully forgetting about the Stone Block Trap they finally get to the treasure room which they must pass through an arch to get to the treasure. Past said arch, the block falls. Hypothetically you could use the block as a sort of elevator through the dungeon, with the lower levels unlocked only when you've reached so far, with the block cutting off your path as you proceed downward thus spurring the adventurers with fear of being trapped forever down here.
Mark, this is the sort of thing I'd enjoy getting involved in, but I'm totally focused now on finishing my first novel. So maybe later. (At the rate I'm getting my novel done, probably MUCH later...)