Zollner is a simple screensaver based on the Zöllner optical illusion (see http://en.wikipedia.org/wiki/Zöllner_illusion for details). Are the diagonal lines parallel or not?
I was somewhat less successful recapturing the illusion in screensaver form, as adding colors and animation tends to weaken the optical effect.
Unzip and place Zollner.saver file in your preferred screensaver directory (usually /Library/Screen Savers).
