The request I received was for a dungeon under a tavern run by an odd man. He asks the party to kill some rats in the cellar and then locks the door behind them. The only real restriction I has was to not, in fact have there be any giant rats. Here is what I came up with. (I'd like to polish it more but if I don't publish it I'll keep tinkering forever).
John Jentilman owns the Two Moon Tavern, a cheerful if simple establishment. Always an odd sort, he constantly complains about rats in the cellar of the tavern. After coaxing the party into helping he ushers them through the iron cellar door . . . and locks it behind them.
Trapped in a bare room with a well in the center of the floor. They must seek a way out of their predicament. (Well leads to room 1)
Here it is in one-page dungeon format and as a word doc.
Update 7/28: Uggh, sorry for the egregious typos. I'm back in the mountains again and will have to fix those when I get back.