While I agree that many of the books above are must-reads (Pragmatic Programmer, Mythical Man-Month, Art of Computer Programming, and SICP come to mind immediately), I'd like to go in a slightly different direction and recommend A Discipline of Programming by Edsger Dijkstra. Even though it's 32 years old, the emphasis on "design for verifiability" is highly relevant (even if "verifiability" means "proof" instead "unit tests").
