Partyfish is a content managment system with many features, including an information sharing system, commenting system, markup language, built-in BBS, and much more. It is completely themable with a bit of HTML and CSS knowledge. It also has a administration interface, which makes managing the information very easy for the administrators.
OPT (Outreach Project Tool) is a PHP general-purpose virtual commonplace for customers and developers to collaborate in developing projects. The system provides documents archive, e-mail archive, request tracker, task management, knowledge base, news administration, newsletter support, and a lot of other features (some project-based, some system-based).
The RealizationEngine is designed from the ground up to facilitate group communication and collaboration. It will store that communication to built and manage an institutional knowledge base. It is accessible from any Web browser or Web-enabled device. Classified information is easily restricted to authorized individuals. Information can be compartmentalized, restricted, or published openly, as appropriate, all from the same system. Ideas are coherently threaded, and every message is searchable in a single location and in the context of the messages related to it.
Zorum is an easy-to-install Web-based forum, message board, or bulletin board. It requires a MySQL database, and the PHP4 script module. Features include an easy Web-based install, embedded administration, a style manager, personalization, threaded and linear views, moderators, password reminder, post blocking rules, bb code, mark unread messages, and much more.