There is a lot of social network analysis software out there. See this link at INSNA for a comprehensive list.
The software I use is called Visone. It works a little bit different from the other applications. Most SNA applications start with a matrix, but Visone starts with the drawing of nodes en relations between nodes. It’s projectleaders are Ulrik Brandes and Dorothea Wagner and I think they did a fabulous job.
Other software I use when I need to do some more analysis is Ucinet from Analytic Technologies.