Just connected this week with Gilad Lotan, Chief Scientist at Betaworks. Gilad has CS background and previously worked in MS for social data analysis especially Twitter and Facebook data. Gilad is now in BetaWorks which is a VC and incubator in NY. One of their most known companies so far is chartbeat a well known company that takes website monitoring from a boring tasks into a game like experience.
Betaworks have now around 11 startups companies with emphasis on data analytics and visual design out the output. Gilad has a blog with many case studies about how visualize large behavioral graphs.
Here are some slick examples:
Some tips from Gilad: when visualizing large graphs the main tricks are doing the right subsampling since you can not draw more than 20K nodes. Gilad is mainly using NetworkX and Gephi for visualization.
Gilad is very supportive of graph analysis and says you have much better signal when using graphs especially with social networks.