At least recently...

History: Six Frigates: The Epic History of the Founding of the U.S. Navy by Ian Toll. Really compelling tale about the first frigates and their actions in the Quasi-War, Barbary Wars and War of 1812. Some pretty badass action, and Toll does a great job. Honestly, someone should make a movie of Stephen Decatur and the First Barbary War.

Auto/Biography: Duty: Memoirs of a Secretary at War by Robert M Gates. Such an inspirational read. Gates defines the word statesman, and you get a fascinating look at both the Bush and Obama presidencies from someone who was both a political outsider and an influential member of the cabinet. Also a good look at just how entrenched the military-industrial-bureaucratic complex is, and how frustrating it can be. Also has some very emotional moments. I'd recommend this to anyone.

Other: A Short History of Nearly Everything by Bill Bryson. Great look at science for liberal arts dorks like me. He uses stories of scientists and their discoveries to explain science in a way that is understandable without too many formulas or jargon. Pretty humorous too!