Elgg is an open source software platform designed to allow people to easily connect and share resources. Users establish personal digital identities and connect with other people, collaborate with them and discover new resources through their connections.

WordPress MU allows you to run a blog network with one single WordPress install. "WordPress MU, or multi-user, is designed to do exactly that. It is most famously used for WordPress.com where it serves tens of millions of hits on hundreds of thousands of blogs each day."

"You can now offer the most advanced web communication tools to your community members. Let them talk online with live video, or upload and share MP3 files, or even keep track of their buddies while they are off your site. Ray turns your site into an addictive communication venue, increasing page-views, returning visitors count and overall rate of your site popularity."

"Dolphin Web Community Software is a free professional software package, created to allow you building your own web community. The script includes a great variety of options, features, modules, add-ons and designs. Dolphin Web Community Software will enable you to build pages of your own site stylish and flexible." The range of features included in this package is as yet unmatched at this price (nothing :>). The software is still licence-based but licences are free.