DotNetNuke
DotNetNuke is a Web Application Framework ideal for creating and deploying projects such as commercial web sites, corporate intranets and extranets, online publishing portals, and custom vertical applications.
Community Server
Community Server is the award winning platform for rapidly enabling online communities and includes all the integrated tools, such as discussion forums, email lists, newsgroups, weblogs (blogs), file galleries, content management, and more to help enable you to create your community presence quickly and easily!
Joomla!
Joomla! is one of the most powerful Open Source Content Management Systems on the planet. It is used all over the world for everything from simple websites to complex corporate applications. Joomla! is easy to install, simple to manage, and reliable.
Mambo
An open source content management platform. Mambo is a full-featured content management system that can be used for everything from simple websites to complex corporate applications.