There are many content management system (CMS) solutions available across the web.  Choosing the right one that fits somone's needs is a difficult thing to do.  Just take a look at this overwhelming list that Bob Doyle put together.  He has compiled well over 2000 solutions.

The method for choosing the right one comes down to requirements and resources.  Content management solutions can be completely free or be outrageously expenisve. Open Source (free) solutions may not cost money up front but require the user to invest time.  One of the other hurdles is actually comprehending the solution.  Not just knowing how to use it, but actually using it to it's fullest potential.  This may lead people to purchasing a licensed system. Here is a good review of some of the best out there.  

After extensive review of online content management Top C Web Solutions has chosen Drupal to be the optimal solution.  This is a site that features companies that use Drupal.  Here is an article discussing a high profile use of Drupal.