I've been throughly enjoying the Gygaxian Democracy series over at Playing DnD with Porn Stars. Basically, Zak posts some kind of prompt - a table to fill in, a keyed dungeon to stock, a list of villians - and the rest of us provide the rest. Crowdsourced DM material, in other words. The results have been mostly fantastic, and I'm really proud of what Smith's prompts and the other contributions have inspired out of me. Here's a few of mine, but really, read the others as well.
1. For a list of villains, I choose to fill in the details for "giant centipede with excellent hygiene"
2. Shriekglass is made from the cries of dead virgins, and is being smuggled into town. Several parties are interested in it, including mine (which I used a Tarot deck to make up).
3. The King has lost his head. The Forces of Badness have made impostures, each of which has a different effect if put back on his body. Like inflating and floating away.
4. The Hammer of Exorcism exorcises things hammered with it. Unless it doesn't, in which case one of a number of things might occur. Like total protonic reversal.