The talk of our office chat room this morning has undoubtedly been Orteil's Game Idea Generator -- a tool that's exactly what it sounds like but no less delightful. You should try it out.
Some of my favorites so far:
As esoteric as some of the concepts are, I can genuinely see this tool serving as a starting point for production on a real game. Some slight tweaks to the ideas might be in order, though.