Genwi is a media social network, save and share, news items, blog posts, video clips, podcasts, feeds, people, all with user profiles, messaging, add friends, voting, comments, add widgets to your profile.
ShareThis Mash Facebook, AIM, MySpace and email contacts into one list.
Huddle This is a network of secure online spaces that combine document, project and team tools with the simplicity of social networking. Pricing from £4.99 a month. Freebie version also available.