Ha - I created
http://iwant.io/ a few weeks ago to test the waters of just this. If it was a software/web/mobile app based on feedback/users I could easily build/share with community. If it was hardware, we could do the pre-work needed for a kickstarter.
I think more ideas will work like this in the future - idea to community, community votes/suggest - idea is built. Win/Win for everyone - make the world suck less!