The Universe in a Nutshell by Steven Hawking is a fun read.
One of my physics professor is always recommending Brian Greene's iThe Elegant Universe, so someday I'm going have to check it out.
Excellent book. I'm not sure if anyone's brought up the 'sequel' yet. The Fabric of the Cosmos
was as engaging, if not more, than The Elegant Universe
For anyone interested in quantum physics, check out In Search of Schrodinger's Cat
by John Gribbin.