I finished Phil Plait's Death from the Skies! Plait blogs Bad Astronomy, which means he's The Bad Astronomer without (so far as I know) being a bad astronomer. The book details the many ways in which the universe can kill us all, from asteroids and supernovae to the final boring end of the universe. I enjoyed the book, but found it a little frustrating. It told me more than I did know, but not as much as I could know. But that's probably only because I have a physics degree or two and wanted more detail than really ought to be in a popular science book.
If you're a compulsive worrier, you may not want this book.