Tricyclists:

http://www.tricyclists.com/ 

First off...I have to say....I'm biased.  I am an active member of the Tricyclists.  Don't let the name confuse you.  It is not a Triathlon focused group - the name stems from being in the Triangle region, not from Triathlon.  That said, there are a good number of tri-geeks on the team.  Great bunch of people.

Franklin Street Cyclists:

http://www.franklinstreetcycles.net/

Doughnut Boy Racing:

http://www.doughnutboyracing.com/

The Tarwheels:

http://www.tarwheels.org/ 

UNC Cycling Club:

http://www.unc.edu/cycling/