A possible approach to EasySubscribe
Background info :
[Derek Scruggs] - I prefer MIME type because it more-or-less mirrors the AutoDiscovery function. The web server simply issues a Content-Type header of application/(rss|atom|whatever)+xml. Client-side aggregators register with the host OS as the default handler for this MIME type and are invoked by the browser whenever it encounters this MIME type. In limited tests, this works well with Netscape, IE and Opera, though apparently not with Safari.