Drupal is the leading open-source CMS used by thousands of organizations around the world including governments, large media companies, many universities, and a plethora of businesses. Many web hosting companies provide quick-install tools to get you up to speed on Drupal within minutes but it can also be installed by simply uploading a file and running a script. You can customize the look and feel with hundreds of themes or extend the functionality with thousands of modules. And since it's open source, you can get in and tweak anything you need--or hire a Drupal developer (which are easy to find) to make those modifications for you.
Tonight, we will use Drupal to setup a full-featured, configurable, expandable website in less than 30 minutes. Many of the same principles can be applied to other packages such as WordPress or Joomla so if you are already invested in another CMS, come learn and compare!