If you happen to want a nice quick read try looking at one or two of the 'Very Short Introductions'. They're usually pretty well written and can provide a nice little overview of some interesting areas often providing further references. Very reasonably priced too.
 Quantum Theory
 Relativity
 Particle Physics
 Cosmology
 Galaxies
Also look at Schutz' introductory book on Gravity (not the green GR book!):
Gravity from the Ground Up
Quote by Bernard Schutz: Preface to the Book
You may already have guessed that this book is not a “geewhizz” tour of the Uni
verse: this is a book for people who are not afraid to think, who want to understand
what gravity is, who want to go beyond the superficial level of understanding that
many popular books settle for. But this is also not an advanced texbook. We shall
steer a careful middle course between the oversimplification of some popular treat
ments and the dense complexity of many advanced mathematical texts.
This book has equations, but the equations use algebra and (a little) trigonometry,
not advanced university mathematics. What is required in place of advanced
mathematics is thought: readers are asked to reason carefully, to follow the links
between subjects. You will find that you can climb the ladder from gravity on the
Earth to gravity (and even antigravity) in the Universe if you go one step at a time,
making sure you place each foot securely and carefully on the rungs as you climb.

See:
Gravity From the Ground Up Website for table of contents, preface and so on.
* Sorry for the .co.uk links!