Good links

http://www.gnu.org/software/gsl/ (including Optimization Package)

http://en.wikipedia.org/wiki/G%C3%B6del%27s_incompleteness_theorems (Godel's incompleteness theorems)

http://www.r-project.org/ (R - statistical tool)

http://lwn.net/Kernel/LDD3/ (Linux Device Driver 3rd edition - Free book)

http://perfeval.epfl.ch/ (Performance Evaluation)

http://code.google.com/p/otkpp/ (Nonlinear Optimization toolkit)