HyperStat Online: Introductory hypertext statistics book. Each chapter contains links to related materials including educational demos and web-based statistical analysis programs

International Society for Bayesian Analysis: Promotes the development and application of Bayesian statistical theory and methods useful in the solution of theoretical and applied problems in science, industry and government

R Project for Statistical Computing: R, also called GNU S, is a strongly functional language and environment to statistically explore data sets, make many graphical displays of data from custom command line, shell has option to save one full environment per working directory. Descriptions, documents, downloads. [Open Source, GPL