Centralisious

A list of SNA Software.

For a very comprehensive list look at this Wikipedia page.

The software I prefer:

Visone: webpage: http://visone.info/

A great visual tool for building and analyse smaller sized networks. Use it in workshops.

UCINet: webpage: http://www.analytictech.com/ucinet/

I use it for more complex analysis.

NodeXL: webpage: http://nodexl.codeplex.com/

Use it for analysis of e.g. Twitter.