ESX Engineering
Ready-to-use software platform that delivers a total environment for development and management of community based sites.

Inchima
Software and portal solutions for online communities. Modules include discussion forums, content management, messaging and directories as well as custom components.

OpenACS (Open Architecture Community System)
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)

Specialty Match Network
Customized software for community facilities such as online matching, polls, forums, weblog, chat and email. Remote hosting services available. [.NET]

Thumper
Perl scripts provide member web space, chat rooms, discussion boards and photo galleries. Remote hosting also available. [Perl]

Web Crossing
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)