I've only read through the chapter on transformations but this seems likely a truly excellent resource. Gratis for personal use.
Combination example code for common things and tutorial.
I think this would be pretty easy to do with gpplot2, but Portfolio looks like its worth checking out too.
Good vim tricks and tutorial page by Jonathan McPherson.
I swear I remember this diagram from the GNU Arch days.
Simple intro to graphic programming in Python. From pfctdayelise.
Nice sort of R thesaurus for other statistical software.
Awesome tutorial with loads of examples, code samples, and graphs. Amazing resource.