I read an article on how to write a book awhile ago and one of their suggestions which I thought was great is to find a classic that you really enjoyed reading and you know was a great seller and change it. By changing it I do not mean plagarizing it I mean totally change it. Change the characters, if it was set in the 1900s change it to the 2000s, if it was a romance novel change it into a mystery etc the only thing that you do not change is the theme of the book that is what has made it successful.