Who is Drupal good for?

• Individuals (manage your content – photos, videos, artwork, music, writing, etc. – without the need of professional assistance)
• Businesses (E-Commerce, Internal and External Blogs, News and Press Releases, Order Tracking, Inventory Management, Social Business Applications, Online Employee Training, Project Collaboration through group-authored content, and more)
• Non-Profit and Non-Governmental Organizations (E-Commerce, take donations online, blogs and press releases)
• Government Websites, Political Campaigns and other Causes (see whitehouse.gov and barackobama.com)
• Education and Research Institutions (capacity to support thousands of accounts, Distance Education, group-authored content, native integration with Moodle)
• News and Content Driven sites (RSS Feeds, Blogs, Image management, and more)

Where is Drupal currently in use?

• Whitehouse.gov, the flagship website of the U.S. government.
• The Symbian Foundation, a non-profit organization that stewards the Symbian platform, an operating system in use by every mobile device developed by Nokia and many other major telecom companies around the globe.
• Grammy.com and Emmys.com, the websites for the Grammy Awards and the Emmy Awards.
• MichaelJackson.com, the official site for fans of the King of Pop.
• FedEx.com, the homepage for Federal Express.

 
List of Fortune 500 companies using Drupal: (http://buytaert.net/tag/fortune-500)
Drupal Case Studies: (http://drupal.org/cases)
Drupal Success Stories: (http://drupal.org/success-stories)