These books have all had a big effect on how I think. Thanks to elliotpp for the idea.
Education and life goals: “Real Lives” (Grace Llewellyn, ed.) and “The Teenage Liberation Handbook” (Grace Llewellyn), though the effect of the TLH has been entirely secondary in my life since I was already doing what it suggests.
Relationships: “All About Love” (bell hooks) — Thank you, Elliot.
Place: “Red” (Terry Tempest Williams)
Mind: “Metamagical Themas” and “Gödel, Escher, Bach” (Douglas Hofstader)
Food: “The Bread Book” (Collister & Blake), “The Moosewood Cookbook” (Katzen)
Philosophy and spirituality: “The Care of the Soul” (Thomas Moore), the “Ender’s Game” series (Orson Scott Card), “Winnie the Pooh” (Milne), and “Red” mentioned above.
And two that aren’t on my shelf, but that had a big effect: A book about the link between depression and hypoglycemia (that sentence sums up what I got from the book, and why I’m not depressed anymore), which was on my mother’s shelf, and the big coffee-table bread book that my parents own, talking in detail about techniques for making bread, both professionally and otherwise, with real, not-dumbed-down recipes.