What's an RSS feed, you might ask. Basically, an RSS feed is a live update of any updating material on the web such as a blog. For example, mine's here - http://controlyourmac.blogspot.com/rss.xml. Well, you can have an RSS feed of anything you like as YOUR screensaver!
1. Open System Preferences ( From the apple icon in the menubar on the top-right )
2. Go to "Desktop and Screensaver" and then go to Screensaver
3. Choose RSS Visualiser
4. Click on the "Options" button
5. In the "feed URL" text box, type in the RSS feed's URL
6. Click Done and you're good to go.