I really enjoyed "A short history of nearly everything" by Bill Bryson.

One of the best general science book presented in a very easy to understand and extremely entertaining way.

I especially like the audiobook version, make sure you get the unabridged version.

And to Johan, I know this one is right up your alley if you did not read it yet, even though you're not really a big fan of pop science books. About the e=mc2, I agree, excellent book, but I do think you have to be a science geek to really enjoy it - with A short history of nearly everything, you don't.