Maybe we should port the voornopnaarpop.nl-concept from free music tickets to books. There is a lot of promo-material available out there. As long as you can create a certain reach.
Just make sure a publisher sends you a book, you publish the excerpt and some links to reviews. People sign up if they want the book. After X weeks you give the book away to a random subscriber.
Or maybe you can just write a review yourself or give it away and ask a review in return. It is all about creating the right (valuable) community / context.
Tip: Listen to an interview with Martin Parr, about how he works and about his new book.