social_network [the libarynth]

http://www.econ.iastate.edu/tesfatsi/netgroup.htm
mapping a terrorist network using publically available data http://firstmonday.org/issues/issue7_4/krebs/
Valdis Krebs / orgNet provide social network analysis software and services to the consulting community » http://orgnet.com
http://smg.media.mit.edu/projects/SocialNetworkFragments/

Search your area for groups with your interests: http://www.meetup.com/
Connecting empty urban space to people (London): http://spacemakers.ning.com/
network to help each ohter to find work (London): http://alpha.signpostr.com/
network for gardeners (London): http://metabolicity.ning.com
network for finding stuff people give away for free: http://www.yoink.com/
p2p finance: loans between people in developed and developing countries http://www.kiva.org/
p2p finance: community funding model for technology startups http://www.growvc.com/
shared physical workspace: http://www.workatjelly.com/
collaborative real-time editors (for Collaborative Design) http://www.twiddla.com/ http://etherpad.com/
handiman-jobs site (Netherlands): http://www.werkspot.nl/