My face-to-face group was founded in the late Eighties by scottedelman and some other DC-area writers who had been to Clarion. A number of successful writers have belonged over the years, including mindyklasky. I don't think there are any founding members still active in the group, but a couple of them still come to the holiday parties.
The membership shifts a lot. Since I joined about ten years ago, it's been as few as seven people. Right now the active list is 12 or 13 people. Some of them write only sporadically—one doesn't write at all, but she critiques very well. Some of our writers, like stephdray, live outside the immediate metro DC area and drive very long distances to participate.
I think one reason the group is still around is that there are so few rules. We don't kick people out if they don't write or if they miss a meeting. We don't set an absolute page limit on how much we will critique. When I run a novel through the group, I can give them the entire m.s. and as long as everyone has at least a couple of months to read it, they'll critique it all at once. We do say that we don't try to do any other stories when we do a whole novel, so I guess you'd say we have a one-book limit.
We also try to maintain a level of civility while still giving an honest critique. I think that's important. And we bring food to every meeting. Writing is a very introverted activity, so it's nice to have the chance to schmooze and nosh with people who are interested in speculative fiction, either as writers or as readers.
And another reason the group is still around—we have great members. Risa, in particular, is willing to do the work of keeping up the address list and the rotating list of whose turn it is to host. We literally don't know where we'd be without her!