webmaven: OK, this is an oddball one, in that a book on Evo Devo is pretty far from CS, but reading it completely changed how I look at software architecture, protocols, formats, programming languages, and a whole range of other CS-related topics.

div0: This book influenced me tremendously. It explains how can random process (e.g. genetic mutation) builds highly non-random structures (e.g. the human eye).