Open-source toolkit for building scalable community-oriented web applications. Features a large database model of web collaboration, and over 70 application building blocks. (Linux or BSD, Aolserver, Oracle or PostgreSQL) http://openacs.org/
Ecreations Software provides a collection of scripts for online communities, such as e-cards, forums, classifieds, chat, mailer and galleries. [Linux] http://buildacommunity.com/
Customized software for community facilities such as online matching, polls, forums, weblog, chat and email. Remote hosting services available. [.NET] http://www.SpecialtyMatch.com
Software and portal solutions for online communities. Modules include discussion forums, content management, messaging and directories as well as custom components. http://www.inchima.com/
Perl scripts provide member web space, chat rooms, discussion boards and photo galleries. Remote hosting also available. [Perl] http://www.usgenealogy.net/infotb.html
Software bundle that includes discussion groups/bulletin boards, integrated newsgroups and mailing lists, full email services, calendar services, auctions, real-time chats and live events. Also offers hosted services. (Linux, Windows, MacOS) http://www.webcrossing.com/Home/Resources/Articles/