Sage

Sage is a lightweight RSS and Atom feed aggregator extension for Mozilla Firefox. It is got a lot of what you need and not much of what you don't. Features include reads RSS and Atom feeds, feed Discovery, integrates with Firefox's bookmark storage and Live Bookmarks, imports and exports OPML feed lists, newspaper feed rendering customizable via style sheets, and Technorati and RSS search engine integration.

What is new in this release:

Version 1.4.13 fixes Feed rendering broken in Firefox 17.

Requirements:

Firefox 3.0b1 - 4.0b8pre