Yet another add-on that shouldn't have to exist, but it does and it works perfectly. It adds a clickable RSS/Atom icon to the address bar when it detects a feed on the page, letting you get straight to the URL(s) without having to manually search the page (and it helps in cases where sites have RSS/Atom functionality but don't give you any way to see/find the URL via normal browsing).

There's not much more to add really, it's extremely simple and you either need it or you don't. If you do, it works.