There are a lot of great a cappella groups out there. Not only that, but there are some great websites out there, as well. Here's a place for you to see some of the other awesome a cappella places the internet can provide.
Intersection Links
The University of Iowa Homepage
The University of Iowa Music Department
A Cappella Groups (people like us...but elsewhere)
Indiana University - Straight No Chaser
University of Illinois - Xtension Chords
University of Wisconsin - Madhatters
A Cappella Places
The Recorded A Cappella Review Board
The Contemporary A Cappella Society