FeedRoller is a lightweight RSS feed ticker.
It is designed to show scrolling headlines from your favorite news sites and blogs, directly on your desktop.

Features:

Supports RSS, and Atom feed format.

Shows news title, summary, age and source.

Customizable interface.

May be "pinned" to the desktop (always visible) or automatically hide when the computer is in use.

May be set to automatically hide when in full screen applications (games, movies etc.)

Customizable keyboard shortcuts to pause the scrolling, pin the ticker, visit the news item and more.

Can import and export feeds from other feed readers (using OPML).

Supports subscribing to feeds directly from Firefox.

Portable.