Drupal

From the official Drupal website:

Drupal is software that allows an individual or a community of users to easily publish, manage and organize a great variety of content on a website. Tens of thousands of people and organizations have used Drupal to set up scores of different kinds of web sites. Drupal is open source software licensed under the GPL, and is maintained and developed by a community of thousands of users and developers.

To learn more about Drupal you can visit the official website here: http://www.drupal.org/

Wallanet has set up a demo version of Drupal so you can try it out. We've included access to the admin interface as well.

The demo version can be found here: Drupal Demo

You can login to the admin panel for this package by logging in with these credentials:
Username: demo
Password: demo

To learn more about this CMS solution and all the other CMS solutions that Wallanet offers go here: http://www.wallanet.com/open_source_packages/cms