This site lets you create an RSS 2.0 feed for an Amazon.com product price, allowing you to track price changes.

To get the feed, enter the Amazon product page URL, or the ASIN/ISBN code:
   
For example, to get a feed for the book "Makers", enter the page URL: http://www.amazon.com/o/ASIN/0596101880/ or just the ASIN code: 0596101880




Easily create feeds with the Prixfeed marklet - drag this: prixfeed to your favorites, and click it when you are on an Amazon product page you'd like to track.