Following up on yesterday's entry on modulo arithmetic, I figured I'd note a couple of books that I've read in the past, and found interesting.
A while back a colleague pointed me to "Hacker's delight". There's recommendations from Josh Bloch and Guy Steele on the back cover. I found it an interesting read, but I remember being disappointed that there were not more general purpose tweaks. My copy of the book has disappeared somewhere or other, so I can't flick back through it and come up with anything better to say!
The book that most inspired me when I read it was Michael Abrash's "Zen of code optimization". It's probably one of the handful of reasons that I ended up doing what I do for a job. Together with his "Graphics Programming Black book" It also caused me to spend so much time iterating on the graphics code in a game I was writing in my spare time, that I never got to write the game.... ;)
Anyway, the really cool thing about Abrash's books, is that a few years they were released for free download in their entirety. Although the 386 processor that they focus on is no longer state-of-the-art, they're still interesting. They seem to still be available from various sources, a list is on wikipedia. Here's the download site on byte.com. Chapter 14 on Boyer-Moore string searching is worth a read.