J.R.R. Tolkien is one of the longest-running favorites in my list of faves. Ever since I was a child, I would let his tales carry me to Middle Earth and even beyond in space and time to the Vanyar and Mayar.
Anything by Douglas R. Hofstadter. Really. You simply can't go wrong. For example, Gödel, Escher, Bach is an amazing book that opened my mind to things I would NEVER have thought about without his insight. Take for example this little ditty that demonstrates the inherent semantic ambiguity of language.
Anything by Kahlil Gibran. Love Letters is particularly moving, and I bought my copy at Barnes & Noble. It's really easy to find it there.
Anything about software.
Gary Zukav has some amazing things to say about a better way to live through understanding the seat of the soul. I know I am nowhere near what he describes as a multisensory being, but I hope I am not a total failure! I think that we tend to "give as good as we get" (to quote Lisa) and that what comes around will end up going around even if we can't see the path to that. I can't tell if what I have gotten is in response to what I have given or if it is meant to make it so that someone else will get what they have given me. All I know is that the dance is much more grand than we can perceive.
For those interested in fractals, and what they do, James Gleick's "Chaos" is a total must read. I am still looking for a link that describes it, but I KNOW Barnes and Noble have it. Interestingly enough, I recently bought this book at Borders and haven't yet read it. Must be all that other time I spent reading the Lord of the Rings and playing LotR games with great friends. Oh... getting married might have had something to do with it too, don't you think?