A man I admire, Richard Feynman.
A pretty cool WYSIWYM (What you see is what you mean) typesetting system, LaTeX. Especially useful if you want to prepare reports, papers and so on. The LaTeX stack exchange is a good place for useful stuff about LaTeX. Another useful site is Detexify, where you can draw latex symbols in a window and get the corresponding code.
LyX is another software based on LaTeX. It is a useful WYSIWYG (what you see is what you get) document preparation system and handy if you want to prepare professional presentations or reports but do not want to delve into the intricacies of LaTeX.
The open directory project, a useful site to search for anything technical and non technical.
A collection of classic ebooks, Project Gutenberg
An essay titled “The unreasonable effectiveness of mathematics” by Richard Hamming.
Random paper generators:
SCIgen: an automatic CS paper generator!
Randomly generate a math paper coauthored with Gauss, Euler or someone else! Mathgen
A randomly generated paper actually gets accepted at a journal! See this. One must be careful when choosing conferences/journals to submit to.