Rael put together some Perl to provide a simple interface to the Amazon recommends system: Amazox. The example on his site is a box with Amazon's current bestsellers...and one for Apple related books best sellers. This code would make it easy to put the top books from any category on your site in your design.

I hope Powells, BookSense, Half.com (all already have affiliates programs), and every other Web bookstore is working on an API. Competition in this area could be good for innovation.