There are lots of great books on being a developer, and not just books about how to code (although they are kind of important). Algorithms, design patterns, compilers, all important. But there are also books that aren't directly about writing code. Books like The Cathedral and the Bazaar, In The Beginning Was The Command Line, Debugging the Development Process, or maybe, Zen And The Art Of Motorcycle Maintenance. Books that talk about the bigger picture. About understanding the bigger picture, how things fit together, and why we're doing the things we're doing anyway. I ran across this list that says it's got 7 Essential Books for Programmers. What books have made a difference in your career, both in your field, and in general.