Just recently I've been looking into a few open source CMS systems. For anyone who doesn't know what they are, it's probably best described as a framework for a web-site. You install the framework system and then add modules for content (forums, blogs, chat-rooms etc). The CMS takes care of all the formatting and user registrations leaving you to concentrate on the content.
A lot of these systems are built using PHP/MySQL so once you have your server configured, you can just unzip the package onto your server and run the admin page. You are then (in theory) able to concentrate on content.
It wasn't until after I installed the Xoops system that I came across a web-site which mentioned one or two more of these systems (OpenSourceCMS). It looks like I'm going to be quite busy trying out a few others as our Cisco classes here use four servers which our students were supposed to add content to last year. Well, one down, three to go.