There's not one that I know of...
A couple of members have talked about ways that we might be able to better communicate club business or other types of members only communications that wouldn't be great for the public domain (e.g., an e-mail listserv or something of the sort). We've also talked about establishing our own message board to increase traffic to our website and to enable us to sell ad space on it (which would pay for the forums and possibly other club activities). There are also all types of free forum hosts out there (e.g., freeforums.org) which could easily be set-up with an area for registered members and an area where unregistered members can still view some of the content.
That said, keeping the majority of our traffic on here has a lot of advantages. The biggest one being that people not in the club can more easily stumble upon us through reefcentral. If the main point of the club is to educate local reefers and build a knowledgeable community for supporting the hobby, then having a members only area (assuming it gets used as the primary communication spot for members) will tend to exclude non-members who might benefit from our conversations and exclude potential members who might join after wandering in to our forum.
I know it's hard for these guys to police the forums and that the best way to stop things from getting out of hand is to head them off before they get there (even though sometimes the handling seems slightly out of line with gravity of the situation). They have established a nice website here with a lot of user information and relatively minimal "junk" to wade through to find that infomation. That's a feat that very few other informational message board sites have achieved...