Social network analysis softwares

Wiki page for social network analysis softwares. It compares features offered by various existing social network analysis softwares. Wiki definition for such softwares

"Social network analysis software is used to identify, represent, analyze, visualize, or simulate nodes (e.g. agents, organizations, or knowledge) and edges (relationships) from various types of input data (relational and non-relational), including mathematical models of social networks"

One such software orgnet, though paid , has given out lots of case studies on "Influence, Diffusion & Contagion" and "Organizations, Projects, & Teams".

Among the tools referred on the wiki, I would recommend to check out NodeXL a free Excel 2007 Add-in for network analysis and visualization.