Hi Dave,
We have not created any special Usergroups at this time. As such, there are no other Usergroups to choose from or join.
The general purpose for Usergroups in the context of JelSoft's VBulletin software is to create special interest groups, such as Moderators, Administrators etc. We could also create unique Usergroups for various registered users. With a member base our size though, we're just not to a point of considering this.
Good question though - thanks for posting it.
Jim