The even offer an API to hook directly into their database of products. Commercial and open source software allows to build websites around the Amazon.com AWS API. The main problem with these sites is usually that they show dynamic URLs.
Which is a reason that you might want to use mod_rewrite.
Anyways, I've been working hard on my new little Amazon Web Shop. It's comming around pretty good. I love the fact that I can offer pretty much everything amazon offers. My next step is going to be working on a wish list I think.