Listening to events in Firefox extensions - Archive of obsolete content
some of the more interesting dom events you may wish to monitor are listed here: event description domlinkadded dispatched when a new html <link> element is detected in the document.
... domlinkhandler the domlinkhandler object is called by the domlinkadded event in order to detect any rss feeds, site icons, or opensearch plugins for the web site.

Event reference
domlinkadded addons specific a link has been added a document.