I just pushed the Amazon eCommerce API datasource to gitHub: http://github.com/primeminister/CakePHP-Amazon-eCommerce-datasource
With this datasource you can easily get listings and items from Amzon in the books, music, etc categories.
You need an access key and secret key from http://aws.amazon.com. Please see the README file in the repository and check the Amazon API at http://docs.amazonwebservices.com/AWSECommerceService/2009-10-01/DG/
Please fork the code [...]