I think you need to do as reddit did -- hire a full time person as community manager (http://blog.reddit.com/2008/10/welcome-erik.html http://blog.reddit.com/20

I think you need to do as reddit did -- hire a full time person as community manager (http://blog.reddit.com/2008/10/welcome-erik.html http://blog.reddit.com/2008/10/welcome-erik.html, http://www.reddit.com/user/hueypriest http://www.reddit.com/user/hueypriest). You can only take technical tricks so far, community management is an AGI-hard problem.