Any medical narrative if you insist on reading something to learn. There is a book called Surviving the extremes which I thought was pretty cool way to learn about how the body survives in some of the extreme scenarios actual people have survived through (how someone survived being in a desert for X days and the physiological changes that he went through as he did, etc..)
Another fun book to read is "Why Do Men Have Nipples"- I enjoyed it. "Complications" (or anything by Atul Gawande), "How Doctors Think" are other ones I can think of. "The Medic" is another interesting book taken from the perspective of a WWII medic on the front lines of battle and the kinds of trauma he sees, and the patients he treated. Interestingly enough I learned quite a lot about Celiac Sprue from one of these medical narratives (Must've been Complications)- and learned more than any medical text taught me. When framed in a story, the reading is interesting and you learn quite a lot. "The Year of the Intern" by Robin Cook was an OK read, written by a resident who lives in Hawaii and he talks about his breaks away from the hospital to go surfing, life as an intern in a hospital with minimal resources, etc.. Lastly, and this isn't really too relevant to medicine is Lance Armstrong's book, "It's Not About the Bike"- you learn quite a lot about cancer treatments and the kind of hell he went through to get his testicular cancer treated (it's also an amazingly inspirational book). Lastly, "Awakenings", is a classic to read if you havn't read it, or seen it in film.
