[johnamata]

Various books on military science/history/geopolitics like Understanding Modern Warfare and Strategy (Lawrence Freedman), and books on Philosophy such as recently I'm reading books by Alvin Plantinga.

I find that reading books from those genres makes me question things more, which I find is a good exercise towards becoming a better thinker and learning how to piece ideas from different areas together.

For software, has got to be "Web Scalability for Startup Engineers" because it gave me a sweeping tour of most of today's software development, and various books on compiler development as building compilers taught me how to decompose things into smaller chunks.