Here are a few of my top picks. More to follow, probably. (My favourite spaceflight books will be in a different list.)
The New Physics
, edited by Paul Davies, is a brilliant one-volume reference work, written at a fairly detailed but still readable level. It has chapters on astrophysics, cosmology, chaos, low temperture physics, and other hot topics. Unfortunately, it's fifteen years old now, and there's a new version out, but I haven't read the new one yet.
Godel, Escher, Bach: An Eternal Golden Braid
by Douglas Hofstadter, won the Pulitzer Prize and is simply one of the most brilliant books written on any subject ever. It explores the intersection between artificial intelligence, creativity, logic, music and art. This is the sort of book that permanently changes the way you look at the world.
Surely You're Joking, Mr Feynman?
by Richard Feynman. One of the most brilliant physicists of the 20th century, he was also one of its greatest characters. This is part of his autobiography.
The Visual Display of Quantitative Information
by Edward Tufte. It's about charts and graphs, and how to design them properly. That might not sound interesting, but this is one of the more beautiful and elegant books that I've ever read. Don't believe me? Take a look at his website.
The Origins of Order: Self-Organization and Selection in Evolution
by Stuart Kauffman. This is a tough book, and I'm not sure that I ever completely understood it. But those moments where I thought I did were intellectually exhilarating. It takes a perspective on evolution that Darwin could only have dreamt of, using insights from theories of complexity and information. He argues that complex systems have self-organizing properties, and that thus natural selection may not have played as big a role in evolution as we might have thought.