Drupal is a leading open source content management system (CMS). It is being implemented by a growing number of businesses and organizations as the platform of choice. Benefits include powerful architecture that enables improved search indexing by Google, Bing, and Yahoo as well as modular add-ons for extended functionality. Drupal is also amazingly stable and fast.
Check out the Beta New York Public Library site built on Drupal. The site is elegant and functional with exceptional workflows. What do you think?