Tools for Social Network Analysis

Here are the list of open-source tools for analyzing social networks

Gephi (http://gephi.org/). Visualization and basic network metrics.
NetLogo (modeling network dynamics)
iGraph (for programming)

Pajek (http://pajek.imfm.si/doku.php). Very extensive functionality via drop-down menus. Open-Source. Works only on windows.

NodeXL (http://nodexl.codeplex.com/). SNA integrated into Excel. Windows-only. Free. In beta.

NetworkX (http://networkx.lanl.gov/). Extensive functionality. Open Source. Scales to large networks by taking advantage of existing C, Fortran libs.

SNA Package for R (http://cran.r-project.org/web/packages/sna/index.html). Extensive, statistics-heavy functionality

Social Network Image Animator (http://www.stanford.edu/group/sonia/)

Books: 
Exploratory Social Network Analysis with Pajek (Structural Analysis in the Social Sciences)
Social Network Analysis: History, Theory and Methodology
Understanding Social Networks: Theories, Concepts, and Findings