System Preferences > Desktop & Screen Saver > Apple > RSS Visualizer.

Click options and you can put in your own RSS feeds. EFFING SWEET. Props to whoever came up with that idea. Probably the first screen saver in history that isn't annoying. In fact, the way I found out about it was going into the system preferences to disable my screensaver entirely.

Update: However awesome of a feature this is, I just realized it's half-assed. You can have a maximum of 1 RSS feed. Which is like having a maximum of 1 girlfriend, or, in other words, something that might've worked in the 90's, but just seems old-fashioned nowadays.