One about food, one about lifestyle: In Defense of Food by Michael Pollan (Check out Omnivore's Dilemma too, if you haven't already). "Eat food. Not too Much. Mostly plants" Can't get much simpler, better for us, and better for the world than that. Radical Homemakers by Shannon Hayes. How to extract yourself from an extractive (i.e., consumerist) culture, get back to basics and not starve doing it.
I found Affluenza a good book too. Think there are a couple of versions, but all give a good overview of how overconsumption is an all consuming epidemic.
Been meaning to read that.
The Michael Pollan books are great. Also, The Ethics of What We Eat by Peter Singer. And Pollan - The Botany of Desire.
My favourites: The Natural Way of Farming by Masanobu Fukuoka; Power versus Force by David Hawkins; and The Humanure Handbook by Joseph Jenkins.