Must Read: Michael Pollan's In Defense of Food.
Photographic work of Chris Jordan, I especially like Running the Numbers in part because I once heard that humans have a hard time conceptualizing numbers over one-thousand (given evolution, why shouldn't we?).
Why I don't eat too much red meat, although I don't mean to imply this article just caused a dietary shift, most of this has been known for some time. Also related, an article on African cattle.