Maybe not as powerful and as polished as some of the other commercial products on the market and used in the intelligence analysis space, NodeXL is definitely the best bargain at zero dollars. Microsoft’s visual link analysis tool (fomerly known as .NetMap) is an Excel 2007 template for viewing and analyzing network graphs, along with a set of .NET Framework 3.5 class libraries that can be used to add network graphs to custom applications. Check out the details here. Thanks to Deborah Osborne at Analyst’s Corner for the tip.
NodeXL: Free Link Analysis Tool