Startup Idea : Platform of development for startups

I am thinking at a platform like odesk only that is for developing startups where someone posts, projects, a plan, technologies used, specifications, and others can join to that project based on his skills, the agreement between parts can be by many types: paid job or profit sharing between parts, i was looking on internet after something like that and i don't found, it sounds interesting. I am a .NET developer and i'd like that this platform to be done with .NET technologies and MongoDB.