There's an idea I've been thinking about in the vein of the "create this" and api competition ideas (and the repo itself I suppose). I've found that on Stack Overflow questions of the form "Is there software that does x, y and x?" will often get locked. However, I think a site like SO for finding software could be really useful. And when you don't find it you've just identified a niche that hasn't been filled that someone could come along and make software for. It would be possible for developers to gauge demand by the number of up-votes/bounties a post gets. It could use many of the same mechanisms from SO like voting/comments/reputation/merging related posts, but perhaps adding some structured ways to describe ideas would facilitate better searching.