My all time favourite book is Harper Lee's "To Kill a Mockingbird". I have had about 4 copies of the book - I read it that much that all of the pages end up dropping out!! Love it.
I also like "The Lovely Bones". I read that years ago, long before the film, and I was just hooked. It was heartbreaking, but I just couldn't put it down. A really good read (although you will need a box of tissues for this one).
I am currently reading "The Lord of The Rings" books. I'm still on the first one, "The Fellowship of the Ring", but I can't put it down. I read "The Hobbit" years ago, and have seen all of the films, but I'd never read the books! I spotted them for 50p each in a charity shop a couple of weeks ago, so I couldn't resist! They are in perfect condition too - bargain!!