Ishmael is first on the list, not because it's the first I read, but because it caused such a strong discontinuity in my thinking. Read it. If you're disappointed, write me and we'll discuss it, but read it first. There are comments by others at Amazon. If money's a problem, check your library. But read it.
James Lovelock's thesis is that the Earth acts like a self-regulating organism. That is, it acts to keep certain important factors within the range which supports life. For example, the percentage of oxygen in the atmosphere has, for millions of years, remained high enough for animals to breathe but low enough to keep forests from spontaneously burning--and it's a pretty narrow range. And the salinity of the ocean has remained constant, also for millions of years, even though salts keep washing in. Consider the couple of places where that hasn't happened--the Dead Sea, Great Salt Lake...

You might not agree with him, but it's a thought-provoking read. A short, important book.

I had heard of the Tao of Physics years ago. It seemed like a pretty fatuous synthesis, something as hard as physics with something as soft as Taoism. But perhaps physics isn't as hard as we've thought, and perhaps Taoism isn't as soft either.

The element the most immediately marvellous in The Turning Point was Capra's amazing concise history of Science. I've never seen the whole of science laid out as well and as understandably. Beyond that, it's the sense he conveys that the time for change is here, now, and must be taken, which drew me. I have to admit, it lies two-thirds finished. I'll finish this review when I've finished the book.

David Brin's marvellous science fiction gently presents settings which have forced me to examine some of my strongest and most unconsciously held word views. And it's always a good read, too.
Ah, Orson Scott Card. A Mormon, hence a missionary. But as far from overbearing as he could be. Ender's Game is the story of (among other things) the military mind, Man's first encounter with an alien race, the excellence of human endeavor. All Card's works have made me re-examine myself.
I might be the only man who has trouble understanding women. But probably not. There might even be women who have the opposite trouble. Tannen speaks with deep insight to this issue. This one changed my life too.
Decline is a book about archetypes--men and women, war and peace, good and evil, success and failure, youth and age, humans and aliens, structure and freedom. Like Tepper's other listed works, it has helped me to consider life in a new way.
Barnes has written a heck of a book about a storm. Given what I've heard in the last few years about how weather is becoming more violent because of global warming, this projection of what it might soon be like would seem like a good idea to examine, even if it wasn't wrapped in such an engrossing story
Heavy Weather's another storm book. Bruce Sterling is a contender for dean of cyberpunk science fiction, and this is one of his best. We can all profit by having a look at what Humanity may be setting in motion through climate change.
Who would think that a book about making perfume could contain the history of the Human race? Of course, lots of the facts are left out, but it's a very compelling look at our spiritual development. And every other Robbins book I've read has also deliciously shined the spotlight on some area of the Human endeavor.
Hyemeyohsts Storm is the result of a marriage of Native American and European cultures. Raised on a reservation, after a youth of rebellion and anger, he has dedicated the rest of his life to learning and teaching the Medicine Way which was the common spiritual tradition among the natives of this country before the arrival of the Europeans. Seven Arrows is lavishly illustrated and crammed both with teaching stories and with the story of the end of the way of life the American natives had been living for centuries, as they were overrun by the European invaders. Made me think. Enriched me spiritually. Made me thirst for more. And Lightningbolt and Song of Heyakoea have helped to slake the thirst.