Select a tag to browse associated projects and drill deeper into the tag cloud.
Dolphin - Smart Community Builder. It is the universal web community script written in PHP and MySQL. Dolphin has a lot of features: Innovative Builders for site customization, Groups, Classifieds and Events , Tags, Rss feeds, Flash Promo and much more
Social Stream is an open source platform on which to build websites with social networking features.
Insoshi is a social networking platform in Ruby on Rails. You can use Insoshi to make custom social networks.