If you have a book you'd like to promote, I highly suggest you check out Authors Marketing Club.
This site is really cool. There are some great forums where authors interact and offer tons of creative ideas. It's a definite plus in the world of books and publishing. A site like AMC is all about authors and a fantastic way to promote your work!
Not only do they highlight Kindle offers, but they mail out about them, and your book could be the feature of the day.
Not enough? Ok... then check out the book trailer forum. Post yours and view others. It's a great source of inspiration!
If you're not an author and just looking for books, they have a HUGE variety of great books just waiting for you.
Sign up and get rolling at: http://authormarketingclub.com