Firefox and Thunderbird each have ways of displaying RSS feeds. Firefox has a cute feature called Live Bookmarks. When it detects that a site has an RSS feed, an icon appears at the bottom right; by clicking it, you can add that feed to your bookmarks. Thereafter, a new "folder" appears in your bookmarks, containing links to the recent stories contained in the feed. Since Firefox already has a solid system for managing bookmarks, it's neat that they can incorporate RSS feeds into that.
Live Bookmarks are cute, but aren't intended to become a full-fledged aggregator system. Thunderbird has one of those, and it's fantastic. Like most modern mail clients, Thunderbird lets you manage multiple accounts at once. For example, I have my personal mail and my work mail visible--but managed separately--in the same program. And it turns out that Thunderbird lets you add another account for "News and Blogs", which serves as an RSS aggregator.
The screenshot on the right shows my thunderbird session at work. My personal and work accounts are visible, along with the collection of RSS feeds I've subscribed to. When you click on a feed, the recent entries appear as "messages" at the top right. Clicking on a message shows the linked content (usually the article itself) in the bottom right.
The important feature here is that Thunderbird can check these feeds regularly, just as it does for your other accounts. It also knows which entries you've read before, so it only highlights the feeds with content you haven't seen. It's really an excellent way to present RSS feeds, and it's the first form of aggregator that might make me stop using my links page.