Home page of the mathematician Herbert Wilf, which offers some of his books for download. I have already read the very interesting "Mathematics for the Physical Sciences".
This is a map of the wheel-ruts of modern English. Etymologies are not definitions; they're explanations of what our words meant and how they sounded 600 or 2,000 years ago.
It seems that the intersection of people interested in Plan 9 and those interested in Lisp is not empty. Several small Lisp implementations, books (some of them in german) about them and lightweight compilation. Nice essay about the advantages of plain
Cool page about (semi)numerical algorithm, including a book in progress, an open source library and a number of interesting links. Also has a mirror of hakmem. The author has also published a book about pi.
A book introducing basic concepts from computational number theory and algebra, including all the necessary mathematical background. Available as PDF under a creative commons license and as book from Cambridge University Press. (Recommended by Mark Wooding).