Darwin's Dangerous Idea, by Daniel Dennett. Should be read by all curious to know the full implications of mechanistic evolution (hint: think about what came before life).
The Mating Mind, by Geoffrey Miller. Must-read for anyone in marketing, or anyone wondering why the other guy got laid and you didn't.
Guns, Germs, and Steel: The Fates of Human Societies, by Jared Diamond. Why are we rich and they poor? Why so few domesticated African animals? Why one big China and a many-state Europe?
The Laughter of Triumph: William Hone and the Fight for the Free Press, by Ben Wilson. Great read about an early 19th C. struggle against unjust laws used to gag journalism. Relevant in today's age of bloggers, etc.
This book really turned my head around and made me realize how there are people (especially ones in the Sales & Marketing realm) out there waiting to sneak one past you. Don't be surprised (not if you can help it), if while reading the book you go "Oh my, someone actually used that trick on me!".
2. The Mindbody Prescription
I understand that some people are skeptical about the theory (TMS) that Dr John Sarno proposes (I was too at first). I'm no neuro-scientist to attest anything in the book, but empirical evidence (experiences of mine and a few others even on HN) seems to suggest the possibility of Dr Sarno getting it right. Anyway, it seemed to help me overcome a problem I had with my wrists and I'm thankful.
2) Paul Wilmott Introduces Quantitative Finance. Pulled this off the shelf at random in a book store 3-4 years ago and found out that modern Finance involves a bunch of mathematics and programming. Started me on a course of learning everything I could learn about the subject and changed my "life arc" very much for the better.
2) Chaos - James Gleick
(I have to mention this one too) The Armchair Universe : An exploration of Computer Worlds - A. K. Dewdney
The power of this book is it's clearity and simplicity. It's not a new age book and not a how-to book. I feel I made a huge leap to a new level of inner tranquility. Maybe it's just the right book at the right time and something I needed to hear but it amazes me how direct the words speak to me.
There's also a short article of the same author on huffington post if you want to get an idea of what is it about.
As the OP asked for two books and we're on HN I'd say SICP
Hackers and Painters by Paul Graham. It is the reason I looked into lisp. A very entertaining read that made me change my opinion on several political issues.
1) Structure and Interpretation of Computer Programs by Abelson and Sussman
2) Kvachi Kvachantiradze by Mikheil Javakhishvili
How to Win Friends & Influence People
The Fountainhead
(both by Ayn Rand)
Rudin, 'Real and Complex Analysis'
2. The Power of Habit
3. Think and Grow Rich
4. The 4-Hour Workweek
5. Pragmatic Thinking and Learning