BuddyPress.org

Nobody wants to sign up to another site. If you do not have facebook and twitter connect you are loosing members. Content is everything. If there is no value to your network people will not stay. Sites need to offer easy ways to share valuable content with their friends. RT buttons, share on FB, digg buttons are a must if you want your users to spread the word about your site for you.

I wouldn’t even worry about members until you have a solid foundation of valuable content. Blog Blog Blog. Post forum topics till your fingers bleed. Add youtube videos and pics.