The Impoverished Social Scientist’s Guide to Free Statistical Software and Resources
http://maltman.hmdc.harvard.edu/socsci.shtml

Open source software, since it is inherently extensible, offers unparalleled opportunities to the researcher to do cutting edge research. Because it is free, it offers opportunities to the student or practitioner on a limited budget. This list concentrates on statistical packages that offer high-level statistical functions and that make source code freely available. Non open source free software is included only when it offers significant functionality that is not otherwise available. A number of software companies offer academic discounts, limited trials or other closed but usable software. This has been adde dto the tools section of Research Resources Subject Tracer™ Information Blog. This has been added to Statistics Resources Subject Tracer™ Information Blog.