Expression Engine

ExpressionEngine is a game changer in the way web site developers can create affordable content management systems for your site. Unlike open source systems like Joomla and Drupal, it is remarkably easy to work within any existing web site design. With a new version due out fall 2009, you can rest assured you’ll see some more ExpressionEngine sites developed by 1310 Studios in the future.
http://www.expressionengine.com