How to Win Friends and Influence People by Dale Carnegie. It is arguably the most useful book I've ever read, albeit with the most embarassing title. As inklesspen mentioned, Elements of Style is a must. Code Complete and the Mythical Man Month by Fred Brooks. Timeless coding wisdom. For a laugh, Catch-22 by Joseph Heller, or Hitchhiker's Guide. Body Language, Julius Fast. Kitschy but fascinating insights into body language. Fabric of the Cosmos, Brian Greene. Brian is a fluke of nature--a physicist who can explain things realy well! Anything by Phillip K. Dick. Sci-fi stories that make you think.
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