Wizzrss.com offers simple RSS and Atom (Supports Podcasts) news reading extension. The free aggregator extension can be used for Firefox. It works with Atom 0.3, Atom 1.0 and all versions of RSS news feeds.

Free aggregator service with the ability to share feeds with others.

Bloglines is a FREE online service for searching, subscribing, creating and sharing news feeds, blogs and rich web content. With Bloglines, there is no software to download or install -- simply register as a new user and you can instantly begin accessing your account any time, from any computer or mobile device. And it's FREE!

Bloglines is a window to a whole new world of dynamic content that is being created and distributed over the new live web. You can make your own personalized news page ...

Feedmarker is a free, web-based RSS/Atom aggregator with bookmarks and tagging.