Neither of these have anything to do with math, so ignore my answer if you are looking for math book reccomendations.

1. The Forger's Spell by Edward Dolnick is a fascinating examination of the psychology -- social and personal -- behind the famous Van Meegeren forgeries. The New York Times has a series right now, Bamboozling Ourselves (Part 1) - Errol Morris Blog - NYTimes.com, exploring the topic.

2. Never Let Me Go by Kazuo Ishiguro is an unsettling, understated book about the "special" students who attend Hailsham boarding school in England and the fate which awaits them.

The first I read a few weeks ago and the second I am rereading. Though not exactly page turners, they are both relatively easy reads (good for summer) that leave one with a lot to think about.