When I finish a really good book, I'm usually disappointed. I don't want the enjoyment to end! But since all books do occasionally come to an end, I'm then on the lookout for the next good book. The Book Seer (http://bookseer.com/) can help you find that next book to read!
Just enter the title and author of the book you just finished, and The Book Seer will recommend other books you might like based on the book you entered. I've found some really good books that I would probably never have stumbled across otherwise.