For the Firefox users out there annoyed by Firefox’s handling of the feed: URI scheme mess, may I please present Feed:Eater, a greasemonkey script which silently replaces feed:http:// URLs with auto-subscribe links that work in your favorite online feed-reader!
Feed:Eater supports: Bloglines, Netvibes, My Yahoo, Google Reader, Pageflakes, NewsGator, AOL, Rojo, and Pluck.

Download it here: Install Feed:Eater greasemonkey script.