TomCoates has a two dimensional model : http://www.plasticbag.org/archives/2003/09/modelling_a_space_for_groupactivity.shtml
Dimension 1, a choice of the role that the shared medium plays :
ambient background (background music in a bar)
inspires but doesn't dominate the social interaction (going to a club where you are there for the music, but not listening attentively)
focus of attention (going to the cinema)
Dimension 2 is whether this is with friends or strangers.
DanahBoyd on culture and SocialNetworking : which http://www.zephoria.org/thoughts/archives/2005/01/09/dealing_with_culture.html#004480 which should also be linked with CreativeClass and her comments on LiveJournal.
Meet people for films : http://www.matchflick.com/
How would it be if you made RossMayfieldsThreeScalesOfNetwork the second dimension?
|| || Ambient || Inspirational || Focus ||
|| Political || . || . || . ||
|| Social || . || . || . ||
|| Creative || . || . || . ||
ZbigniewLukasiak is developing more communication dimensions here : http://zby.aster.net.pl/kwiki/kwiki.cgi?UseTheWholeSpectrum