Tiger users will have used the RSS Visualizer screen saver; if not check it out. But, by accident, I managed to set it as my desktop as well -- and it's really cool. I had already installed DesktopEffects when I was running Panther, and the app picked up the RSS screen saver I had set in 10.4.
This appears to be stable under Tiger. The setup is straight-forward; launch and open the RSS Visualizer located in /System/Library/Screen Savers/RSS Visualizer.qtz. The only drawback is that it's not keyboard interactive like the screen saver is.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050521042959771