What kind of group? Ravelry? Yahoo? Something else?
For Ravelry, I think I'm in one group -- the KH one. I haven't spent a lot of time over there and I haven't explored everything they have to offer.
Knitting is kind of a second hobby for me and I spend my online time elsewhere. KH is my primary knitting social group (here, not on Ravelry) and I mainly use Ravelry for it's database.
I'm not in any Yahoo groups anymore, although I do stumble across ones now and then. The couple I had joined in the past weren't very useful to me and now I just stay out of them.