I ran across a few interesting tidbits about RSS today that illustrate the powert of creating Web enabled data directories. First, Adrian Holovaty has started to offer custom RSS feeds for his blog. The RSS feed is essentially a generator that takes an optional parameter which represents a search term or filter for the RSS feed. Good idea. The second is interesting as well, but also shows the real power of RSS, Web services, and a properly designed, RESTian interface.
Paul Bausch has created a tool for creating custom RSS feeds from Amazon. What's neat however, is that this is just a XSLT stylesheet on the RESTian Amazon Web services interface.
These two posts are actually interesting to compare. In the first, RSS is being created and then filtered (or at least the rss generator program makes it appear that way). In the second, an RSS feed is being created by transforming the output of a much more general program for creating XML data feeds. This is a great example of the power of building web enabled data sources. Amazon didn't set out to create an application for building custom RSS feeds of their data. But exposing a public interface to their data allowed others to do that and hundreds of other things that Amazon would have never thought of.