"What is the book that changed your life? (not novels or religious texts)"
I think it's a wonderful way to connect in a less superficial way and learn a little more about each other. It's also a wonderful way to discover new books worth reading.
This is one of them:
Zen of Code Optimization
Provides unique coverage of Intel's Pentium chip. Explores hardware programming aspects that affect code performance. Features innovative optimization techniques not found in any other book. Includes the useful Zen timer-a hands-on software tool for measuring code performance. Presents creative "right-brain" Zen approaches to the art of writing PC