I just wanted to point out a minor, but potentially very useful, improvement to the AWS OpenSearch Engine on unto.net.
Previously, each item returned in the OpenSearch RSS feed appeared to be unique and independent from one another in the eyes of a blog reader or RSS aggregator. This was problematic insofar as an item could change prices a few times during the day, and each change would create a new entry in the feed. This was annoying more than anything else, and significantly limited the value of saved product searches.
The fix was to add a <guid /> tag to each item. That unique id is set to the ASIN of the product itself plus the unto.net associates ID to distinguish it from any other RSS entry pointing at the same product. Now, price changes or product information changes will cause the blog reader to show that there are updates, but not create an entirely new entry.
For example, a search for Mac OS X Tiger can now be subscribed to in Bloglines, and you will only be informed when the price or product info (most of which I leave out anyway) changes.
Try saving a few searches yourself. There are more categories than just the five shown above. Cooking is an especially good one.
Question -- would people find additional product information useful? I was aiming for lightweight, but a little text might be nice...