Network Analysis Software: focus on F/OSS

What do you use for network analysis? I found the Wikipedia list of network software entirely overwhelming. I wanted to test out some of the introductory tools, but avoid the trap of sinking my time into a dead-end software project. (Remember learning Minitab in freshman statistics? How often do you use Minitab today for anything other than freshman statistics?)

UCINET came very well recommended by several friends who use social network analysis for business and politics. I wasn’t sure whether it would turn out to be a proprietary, one-way data sink like Blackboard or a useful, interoperable tool for analyzing and sharing data.

The Journal of Statistical Software published an issue about Statnet in 2008. Esteemed authors in the field wrote a number of great tutorials about Statnet, which is an umbrella package for most of R’s network analysis tools.

UC Irvine hosts a wiki on network analysis tools. That wiki describes a few of the F/OSS tools. All the links contain tutorials. You have your choice of tools that are freestanding, part of R, or part of Sage/Python. If you’ve got a good reason to go with one of the other F/OSS tools, such as Guess, Pajek or Networkx, please comment with your thoughts.