"Hacker's Delight" by Henry J. (Hank) Warren. Despite the unfortunate title[0], it teaches (with code) numerous tricks, algorithms, ideas, that really improve performance and function of programs.
[0] not "hackers" as in those who try to crack into systems, but rather as in those who enjoy writing professional, clever, and efficient code.
Get the 2nd edition, of course. It's three times as long.
I don't know if I've ever really learned anything from Hacker's Delight, though. It's more of a cookbook. If I learned anything it's that a lot of dead CPU architectures were hard to program.
[0] not "hackers" as in those who try to crack into systems, but rather as in those who enjoy writing professional, clever, and efficient code.