Using the bookmarklet to subscribe to a blog or site with Fever, a self-hosted RSS newsreader from Shaun Inman, will display all feeds found for that site. In the cropped example below—Steam’s collection of gaming and product blogs—the site has around 20 feeds, and Fever found all of them.
You can subscribe to only the feeds you want and add each feed to one or more of your groups. Once you click “subscribe” at the bottom, the subscriptions are added, and you are redirected back to the page you were originally browsing.