The R programming language, sometimes described as GNU S, is a programming language and software environment for statistical computing and graphics. This is the main page for the R-project, from here you can downlaod the software and packages moreover there is almost all documentation you need.

LaTeX is a document markup language and document preparation system for the TeX typesetting program. From this link you can download the program and some manuals.

C programming.com is a web site designed to help you learn the C or C++ programming languages, and provide you with C and C++ programming language resources.

GCC, the GNU Compiler Collection.