You can basically develop any type of site in Drupal as long as it doesn't require too many extensive features that are not addable via modules and such.
You can build anything with Drupal, developers already proof that you can create a own: Twitter, Facebook, Youtube, Digg, Flickr, Craigslist etc. with Drupal.
It all about your skill. You can built any kind of site using drupal. oDesk made with drupal, I think it may help you to understand the power of drupal. Basically you can build anything with drupal, as long as you can do same thing using PHP.