Drupal is another CMS that has a very large, active community. Instead of focusing on blogging as a platform, Drupal is more of a pure CMS. A plain installation comes with a ton of optional modules that can add lots of interesting features like forums, user blogs, OpenID, profiles and more. It's trivial to create a site with social features with a simple install of Drupal. In fact, with a few 3rd party modules you can create some interesting very sites with little effort.
One of Drupal's most popular features is the Taxonomy module, a feature that allows for multiple levels and types of categories for content types. And you can find plenty of professional Drupal Themes, which are ready to be customized and worked with. You can also grab Drupal Plugins.
Drupal also has a very active community powering it, and has excellent support for plugins and other general questions.
You can also hire a developer to complete a range of tasks for your Drupal site for a reasonable fixed fee.
