Schneier on Security: A Revised Taxonomy of Social Networking Data
http://www.schneier.com/blog/archives/2010/08/a_taxonomy_of_s_1.html social network user data categorization by Bruce Schneier (useful)
Socialmedia
The Real Life Social Network v2
http://www.slideshare.net/padday/the-real-life-social-network-v2 A great presentation [from google] about how people interact socially in the real life and how current social networks represent them. (Needs about 30 min to read)