OPML Taggregators

del.icio.us is a social bookmarking site that I've written about before. It allows you to tag links so that you can categorize them more easily (i.e. you'll actually do it!) than the traditional bookmarks feature in browsers. As different people tag things you can build up a model of link popularity and metadata based on statistics rather than a more brittle taxonomy. For a long time, I've wanted to do the same thing with subscriptions - the issue has always been packaging the result in some form that would be useful. Danny Ayers recently wrote a script that converts the links that he has tagged with a specific tag as an OPML Reading List. It would be really nice if del.icio.us did this itself by determining that something is an RSS / Atom subscription (like they do for mp3 / mpeg files) so that you could get a reading list that was all of the subscriptions tagged with "opml" and "reading list". It's a little more difficult than that because mp3 / mpeg files have distinct mime types whereas RSS files typcially do not. However, it wouldn't be too hard for the service to parse the content you tag to determine if it is RSS (Yahoo! My Web already caches the content you link to). Yahoo! could even serve the RSS from their servers so that it takes more load off of the individual RSS publishers - this is pretty much the FeedBurner model - and maybe even just aggregate the content together. There are some server based aggregators (Rojo as I recall) that will support tagging of feeds but 1) I use a desktop aggregator and want it in a form I can use and 2) I already use del.icio.us for tagging and don't want to create a different set of tags for this. Of course del.icio.us has an API so it wouldn't be too hard for other services to re-use your existing tags if they wanted to.