A central source of all things social networks: http://insna.org the home of the International Network for Social Network Analysis.

Wikipedia page on Social Networking: http://en.wikipedia.org/wiki/Social_network 

The SOCNET-L List is a great resource: http://www.insna.org/INSNA/socnet.html - the email list for all things social networks.

Microsoft Research has a project to build a social network toolkit for Excel called C#UNG (C# Universal Network Graph) which generated the following from our Newsgroup data:

            http://sgfoocamp08.pbwiki.com/f/Microsoft%20Research%20C%23UNG%20Image%20of%20Usenet%20Newsgroup%20Reply%20Social%20Network.jpg

http://research.microsoft.com/research/downloads/Details/bd44899b-634e-4f1e-a69c-36546fa14529/Details.aspx

Books on Network Theory:

http://www.amazon.com/Network-Analysis-Methodological-Foundations-Computer/dp/3540249796/ref=sr_1_1/104-4287440-3883109?ie=UTF8&s=books&qid=1181939945&sr=1-1  

Wasserman and Faust: the “bible” of Network theory

http://www.amazon.com/Social-Network-Analysis-Applications-Structural/dp/0521387078/ref=sr_1_1/104-4287440-3883109?ie=UTF8&s=books&qid=1181940145&sr=1-1

Workshop presentations on limits of network visualizations and some innovations:

http://www.cs.umd.edu/hcil/sna-workshop/  

Perer and Shneiderman: Network Visualization via Semantic Substrates

http://www.cs.umd.edu/hcil/sna-workshop/documents/Perer-SYFDiscovery.pdf  

Visualizations of Science - Katy Borner

http://ella.slis.indiana.edu/~katy/  

http://grants.nih.gov/grants/KM/OERRM/OER_KM_events/Borner.pdf