by Martin Kliehm on WordPress.org
The plugin checks for machine tags with ISBN or ASIN numbers, gets the product data from Amazon, and displays it in the sidebar or in a blog article.

Admin interface
Simple inclusion of Amazon items through machine tags.
book:isbn=1234567890 or amazon:asin=1234567890. Works with native tags from WordPress 2.3 and later, Bunny’s Technorati Tags, and Jerome’s Keywords.You can edit the server-side, semantic and valid XHTML output via XSLT, change the CSS, or translate the admin interface through PO-files.