The George H Thomas' Invincibles (GHTI) are an interesting concept in the world of Civil War reenacting. This group is actually a confederation (no pun intended!) of several smaller "mess" organizations with a similar mission.
The site itself is rather simple, and very easy to navigate. It acts much like a portal to the other individual group sites, plus it covers the GHTI as a whole.
The idea of GHTI is very appealing to me, since it seems to be a successful cooperative effort to pull together like-minded groups. I really enjoy the Events page - every event seems to almost a travel ad. Makes it look very appealing -- something groups need to do help members decide on what they wish to attend. It also specifies the impression that the groups are aiming for.