I've still got some work to do, so this is just a "hey, it works" sort of post.
John Tropea posted last week about an OPML hack for del.icio.us to which I responded with a more dynamic example and to which another reader asked, "Why bother?" Fair enough quesiton, and here's a better answer by way of example.
IÃ¢â‚¬â„¢m using MySQLicious to mirror my del.icio.us bookmarks to a local database (for several good reasons). Now that I have a local copy of those bookmarks and all the del.icio.us tags and other del.icio.us metadata, I can remix it however I want.
The first thing I've done is create an OPML file on-the-fly, where every del.icio.us bookmark is rendered as an RSS feed item with the bookmark's URL as the feed htmlUrl and the xmlUrl is an RSS feed of a Feedster search on the bookmark's URL.
Here's the raw OPML file.
Here's how it looks in Optimal.
Notice that there is a query string parameter "addfeeds." Without this parameter, the OPML is simply rendered as a link list. An addfeeds value of "feedster" adds the search feeds. Eventually, I'll have some additional query values I could use here, such as Technorati.
Here's the source.