If you want to test run some of the free content management systems out there, without having to go through the rigmarole of installing and configuring each one first, try...
http://www.opensourcecms.com/

On the downside, only PHP/MySQL CMS systems are included.

On the upside, the site also demos blogging, ecommerce, forums, and wikis, among other systems.

3 highly recommended CMS systems right now are Plone, Mambo and Drupal. Plone is meant to be the most flexible and thus the most complicated to learn!