CG-Amazon gives you the ability to track your own 'database' of products, and tag them with custom keywords. Then a single function call will grab all, some, random, one, etc. from a given tag and output it for you. That's great for 'now reading' listings in the sidebar.
In addition, with CG-Inline, you can put links to amazon products into your posts/pages with a simple tag plus the product ASIN. CG-Inline+CG-Amazon will do the work to lookup the product (and cache information local), and create the output HTML. The inlined products don't have to even be 'in your database' to display -- but if they are, the system can also show any custom 'notes' you've attached to a given product.
Pretty cool. It's a big system, I've tried to simplify ways to use it as much as possible, while keeping it dynamic (that is, it uses the ASINs and live looks up stuff from Amazon when needed -- as compared to products where you embed the 'final' HTML directly into your posts or sidebar, fixed for all time).
It's part of my overall CG-PowerPack of WP plugins.