I recently attended the first Drupalcamp South Florida and the Key Note speaker was Brian House from Acquia. His talk involved community building with Acquia Commons.
I had heard of Drupal Commons, but I wasn't aware of all of the features that it provided out of the box.
There are a lot of quality contributed Drupal themes available that can be found at http://drupal.org/project/themes You can probably find one that will suit your needs for the most part within the first few pages of this listing.
What if you want to customize it and tweak it a little bit though? Perhaps everything about the theme is perfect, except for a few minor details that you would like to change
A client with an initially small budget approached me about a need for a site. Brian Kocher Consulting needed a site completed quickly on a limited budget.
His initial functional needs were for a user blog, an events calendar, and some standard static pages along with a few social networking links.
Utilizing Webenabled, who is now offering git in beta, his site was complete and functional in less than two weeks.
