I am currently reading The Philosophy of Sustainable Design by Jason McLennan, and it is the most captivating book that I have read in a long time. I really highly suggest reading it; here is a good quote from the book that basically sums up its premise:
My past has taught me two important lessons; that we have an amazing capacity to damage the habitat of all living things while building our own,
but we also have an ability to heal it through good design.
also makes a great gift for the environmentalist in your life