If you are a Mac user, check out this really nice typographic screensaver from London-based graphic designer and programmer Simon Heys.
There’s no ‘Reset to defaults’ option, and I think I went kind of crazy with the typefaces because it eventually gave me an error and refused to load. So if you want to reset it, find the com.simonheys.wordclock.plist preference file in Library › Preferences › ByHost and trash it. Then relaunch System Preferences and get customizing. Or leave it as is—I do like the default configuration.