Free and almost free, more popular CMS

[Chao]

These are the few popular ones:

http://www.drupal.org Platform and content management system
http://www.joomla.org Award-winning system to build Web sites and powerful online applications
http://www.cmsmadesimple.org For corporate websites, or the website promoting a team or organization
http://www.xoops.org eXtensible Object Oriented Portal System
http://www.plone.org Running on top of Zope and the CMF
http://www.TYPOlight.org Specializes in accessibility (back end and front end
http://www.eZPublish.org Professional PHP application framework with advanced CMS
http://www.dotCMS.org Java Open Source Web Content Management System
http://www.MODxcms.org Powerful framework to deploy and secure websites and web applications
http://www.SilverStripe.org Flexible, open source programming framework, and CMS
http://www.Mamboserver.com Dynamic portal engine and content management system
http://www.miaCMS.org Content Management Made Easy
http://www.ImpressCMS.org Community developed Content Management System
http://www.Typo3.org Small to midsize enterprise-class content management system
http://www.Textpattern.org Flexible, elegant and easy-to-use open source content management system
http://www.e107.org Portal or CMS using PHP and MySQL