If you read the book Fast Food Nation by Eric Schlosser (and if you haven't, I really suggest it), then you should definitely read The Omnivore's Dilemma: A Natural History of Four Meals by Michael Pollan. It deals with where our food comes from, and the problems with factory farms and non-sustainable agriculture. Even if the topic doesn't particularly interest you, the writing is superb. Pollan gives his own personal experiences and opinions in a non-preachy manner, and the book ends up being hopeful, and gives me the incentive to start being more conscious of what I eat (this book doesn't say that we shouldn't eat meat, although it does respect the vegetarian option, instead, it suggests that we take a better look at where all our food came from and how it was produced). Anyway, for health, political, animal-rights, environmental reasons, and sheer entertainment value, this book is (in my mind) a must-read.