Sage is a lightweight RSS and Atom feed aggregator extension for Mozilla Firefox. Sage has a lot of what you need and not much of what you don't.
Here are some key features of "Sage":
· Reads RSS (2.0, 1.0, 0.9x) 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
· Technorati and RSS search engine integration
· Support for the following locales: Argentine Spanish, Catalan, Chinese, Czech, Danish, Dutch, Finnish, French, German, Greek, Hungarian, Italian, Japanese, Korean, Polish, Portuguese, Russian, Serbian, Slovenian, Spanish, and Swedish
Requirements:
· Mozilla Firefox 1.0 - 2.0.0.* ALL