Programming Pearls - 2nd Edition by JonBentley
ISBN 02-0165-788-0 Not to be confused with the book ProgrammingPerl, originally by LarryWall and RandalSchwartz. Programming Pearls is a handy book for code tuning, performance enhancements and general troubleshooting. Before I mess with a working program, I look here first for advice. This book is part of the ever-growing PatternPerson GreatBooksList. -- ToddCoram
I think it goes deeper than "code tuning, performance enhancements and general troubleshooting": it encourages people to think about programming in a systematic and lateral way.
See also: http://www.cs.bell-labs.com/cm/cs/pearls/
Reading this book convinced me that I need a new job. I read the book and thought, in quick sequence: great stuff, good book; wait a minute, this material has no connection with my work, what a scam; I wish it did, though; so, hang on, this is good stuff, so my job must suck.
See also MoreProgrammingPearls.