0xDECAFBAD: Phil makes a suggestion that seems ideal to me. Don't link to feeds directly, don't use a funky protocol, link to a "playlist" of feeds.
Randy: Leslie Orchard makes a case for Phil's application/feedlist+xml. Now that I see this a little more thought out, I don't like the need for a new XML. If everybody just returned the correct media type and added one link element to their RSS channel, then we don't need another XML format.
Randy