Would also like to mention that the Elements of Style by William Strunk and E.B White is an all-time great book on non-fiction writing. It was required for my Newspaper Fundamentals class in college and I've used it so much since that the creases are wearing thin.

There's another fantastic book—On Writing Well—that is a recurring read for me. An aside—I was in one of the early programing bootcamps, The Starter League. My class was held in 37signals office. Jason Fried and some of the other 37signals designers were in this class with me. One day Jason stood up and answered a few questions. One of the other students asked him about books. He walked over to a closet and opened the door. There were hundreds of copies of On Writing Well. That's the book he'd gift to people.

That always struck me as interesting. Especially since he'd written (or co-authored) several books at that point.