Stephen King's The Stand. No matter what your preconceptions about Stephen King are (whether you've read any of his other works, hate movies based on his work, what have you), The Stand is absolutely phenomenal and completely superior to all of his other works.
Audrey Niffenger's The Time Traveler's Wife is also amazing. I will warn you that it is unabashedly romantic, if you're not into that sort of thing. I, generally, despise most anything "romantic" in nature (never saw The Notebook, refuse to watch nearly all chick flicks, would rather watch people get esploded and so forth) but this book is a really huge exception to that rule for me. It's fantastic. They're making a movie out of it, too, actually.
I like Jeffrey Deaver as an author, also if you like books with some historical background, check out Wilbur Smith. Gokes Gokesybutton Furbytoo Xaanali Zaan