<link rel="alternate" type="application/rss+xml" title="RSS Feed"
There is a way to do linking just using HTTP through the LINK header (as seen in POWDER. It looks very similar but is more powerful, from the IETF draf document:
Link: <http://example.org/>; rel="index start";
Defines 4 links for http://example.org/, three outbound (index, start and http://example.net/relation/other) and one inbound (copyright).
More information: HTTP Status Report and LinkHeader.