Hi tom_b, I'm one of the co-organizers of the NYC Clojure meetup. I don't know if that's the one you attend, but I'm definitely interested in any specific ideas you might have for better introductions and ice breakers.
My only recommendations are quite generic - for smaller meetups, make sure a group introduction is on the agenda and actually happens. Might be nice if there were easy ways to become more active in the group, but this is hard for the meetup/talk format.
I'm definitely not being critical though - I feel lucky enough to have a Clojure meetup happen in my general area. Mostly it falls back on me, as an interested-in-the-community hacker to find a way actually be social and integrate myself into that group.