hebig.org/blog
Personal webnode of Haiko Hebig

AND NOW FOR THE REALLY COOL STUFF: SIMILARITY MAPS
If you thought the Google look-alike thing is cool (as we did), you didn't see the Similarities Map application yet: search for an item and see its immediate similar neighbors clustered together in a dynamic image. We think this example is pretty impressive.

AMAZON VIA PHP I: URL, ARRAY BUILDER
PHP Amazon Search is intended as a starting point for PHP developers who want to go the REST-way. The provided classes contain functions for constructing URLs with developer key, associate ID and search term, retrieving search results, and parsing the XML into PHP arrays. Especially the latter might be of good help.

AMAZON VIA PHP II: WRAPPER
Daniel Filzhut has an extensive set of PHP functions for interacting with the Amazon API, too. They are free for non-commercial use.

PYTHON WRAPPER
Mark Pilgrim has written PyAmazon for this.

OTHER APPLICATION EXAMPLES
Weblog XML feed, Google API and Amazon API combined: Book Watch "retrieves an XML feed containing the books most mentioned in current weblog updates, finds relevant links at Google, item information at Amazon and as the result presents a constantly changing list of book that are generating buzz around the weblog community".

Mockerybird has a constantly updated list of applications using the new API.