I'm working on exactly this area at Sparkmuse. We're trying to build -the- startup community including all of the related disciplines (hackers, designers, marketers, etc). Although obvious, 4chan has an enormous community which is why they have so much activity. Successfully growing a community to that scale is immensely difficult.

Our community is based on a mission to help tech entrepreneurs succeed. That includes giving feedback on ideas, helping cofounders meet, providing discussion areas, and hooking founders up with good deals. If that is something you find interesting, I'm actively looking for people to join up with us and make it a reality.