Yeah, as TG mentioned way back on this old topic, CG-Amazon is one of the long-standing Amazon interfaces for WordPress. It delivers a wide range of functionality, from "Currently Zzzzing" lists, to a random selection of items from your 'own database' of amazon products, to listing your Amazon Wishlist items, and more. It also has a sample script for a "product database" for your site, which many users have just dropped in and used as is.
Also, in combination with CG-Inline, you can embed >dynamic< product links within posts -- i.e., if you want to show things like pricing information, it'll live-update (well, cached, approximately every day or so by default).
It has advanced functionality that barely any of the users have touched as there are a couple of SIMPLE function calls to extract all sorts of cool lists of products from Amazon...