1) **** “The New Quantum Universe” by Tony Hey and Patrick Walters, 2004. This book is the best all round source of information about quantum mechanics. There are lots of pictures, diagrams, history, experimental evidence and depth to the discussion.
2) *** "Quantum: A Guide for the Perplexed" by Jim Al-Khalili, 2003. A very good book with great illustrations but sometimes lacking in the depth of its explanations.
3) *** "Where does the Weirdness Go?" by David Lindley, 1996. A very good discussion of what is weird in quantum mechanics and why we don't see it in our everyday lives. Full discussion of the various interpretations of quantum mechanics. In 2007 he wrote ***"Uncertainty: Einstein, Heisenberg, Bohr and the Struggle for the Soul of Science" which is an excellent treatment, in depth treatment as to why quantum uncertainty is such a radical departure from classical physics.
4) *** "A Shortcut Through Time: The Path to the Quantum Computer" by George Johnson, 2003. A thorough explanation that almost made me feel like I understood what a quantum computer was.
5) *** "The Quest for the Quantum Computer" by Julian Brown, 2000. This is a great book, if you are interested in the math and computer science of quantum computers.
6) *** "How to Teach Physics to Your Dog" by Chad Orzel, 2009. The book is both in more depth and at the same time more understandable than most others. I liked the fact that it wasn't afraid to put a bit of math in and he focusses on polarized light as the best vehicle for understanding quantum weirdness- somehting I have been convinced of for a long time. The dog angle is surprisingly useful.