Content Management Systems
http://www.cmsmatrix.org/matrix/cms-matrix
The CMSmatrix site allows users to discuss, rate, and compare free and non-free content management systems. It provides an extensive list of CMSs and allows users to search for systems and compare features side by side in a matrix.
http://drupal.org/
Drupal is an advanced portal with collaborative book, search engines, URLs, online help, roles, full content search, site watching, threaded comments, version control, blogging, and news aggregator. A special group, Drupaled, focuses on education.
http://www.geeklog.net
Geeklog is a PHP/MySQL based application for managing dynamic web content. It is a blog engine and content management system with support for comments, trackbacks, multiple syndication formats, and spam protection.
http://www.joomla.org
Joomla! is an open source content management system. It can be used for simple websites or complex corporate applications.
http://www.opensourcecms.com
The OpensourceCMS site gives you the opportunity to "try out" some php/mysql based free and open source software systems. The administrator username and password are given for every system.
http://mamboserver.com
Mamboserver is a content management system that features inline WYSIWYG content editors, news feeds, syndicated news, banners, mailing users, links manager, statistics, content archiving, date based content, 20 languages, modules and components.
http://www.typo3.com
TYPO3 is a free open source content management system for use on the web and in intranets. It features a set of ready-made interfaces, functions, and modules.
http://plone.org
Plone is a ready-to-run content management system that is built on the powerful and free Zope application server. Plone is easy to set up, extremely flexible, and provides you with a system for managing web content that is ideal for project groups.
http://wordpress.org
WordPress is a personal publishing tool with focus on aesthetics. It features a cross-blog tool, password protected posts, importing, typographical aids, multiple authors, and bookmarklets.