Ok, here's my €0.02 on the one-click feed subscription issue. The first €0.01 is that it shouldn't be necessary for people to put other people's icons on their page. None. Imagine the Beatle's White Album with an orange [XML] in the corner... Clients only need to be a tiny bit smarter, use autodiscovery to pick up the <link> elements and make an appropriate offer to the end user. FireFox is well on the way with this.
For the other €0.01, where links are provided, the server can help by pumping out the feed with the appropriate mime type. From what I've heard this is likely to happen out of the box in many cases with Atom. Given an appropriate mime type, there's no need to use pseudo-URI schemes like
feed://. Almost. There is another small piece of the puzzle that's missing, at least for RSS 2.0.
Providing a link to the feed itself within the feed, for the client handler app to pick up. RSS 1.0 should provide this already, as the
channel resource. (I just noticed that TypePad at least gives the URI of the (HTML) blog instead, oops. Atom does in... does it..? Time for a post to list...)
For RSS 2.0 this problem can be solved by adding a namespaced element which points to the source feed. Ok, so you still have the problem of not being able to use the mime type in most cases. But I have a cunning plan. What if people are encouraged to add a stylesheet reference to there feeds? i.e.
<?xml-stylesheet type="text/xsl" href="rss2html.xsl"?>
The stylesheet itself could be on the local server or on some friendly person's. The XSLT would render the feed in a human readable fashion, with a note saying "this is a feed" and then a set of links for either subscribing to a client- or server- side tool. Those links would be derived from the extra element pointing to the feed. This solves the problem of not being able to serve with a registered mime type, as well as presenting the end user something useful rather than a page of code.