Atom was Google's answer to RSS back when they cared about an open web. As far as I can tell, everything that handles RSS also handles Atom, and they're exposed in the header in the same way.

Firefox users can right click on the browser chrome, go to Customize, and add a subscribe button that lights up when a page has a feed. It's not as snug a fit as what used to go in the address bar, but it still works.