Mesmer draws colorful sinusoidal function lines on the right half of the screen and then cycles through the colors along those lines. To end the simulation, click the mouse and wait for 10-15 seconds until the cycle is complete.  It will...

Meltdown is a super tiny app (1.9KB!!) that makes your 9" monitor screen melt :) Meltdown is a much cruder and crashier clone of Melt.  

IconBounce is a very early Macintosh kind of screen saver.  It's more like just a demo that bounces B&W icons all over the place.  This app features 1980's apps/games icons, some are more obscure than others.  

Iconer can be used as a prank.  All it does is on launch, it randomly pops thousands of B&W system icons to fill your desktop.  You can stop it using CMD-Q.  

GomerFun renders a couple colorful patterns across the entire screen (altough, since resolutions in 1986 were not that high, some patterns obviously won't fill 1024x768).  Not much information available on this very old piece of software,...

Bahaus is what looks like a demo.  It draws rectangles of various sizes at random positions, alterning between B&W.  Clicking exists.  There doesn't seem to be anything else about it.  

MacFishTank simply puts a bunch of big green fish swimming across the screen while you work.  This RealBasic app is silent. From the author: MacFishTank was devised one day, as a joke by Kris Harris, the overlord of Wild Cat Software. After...

Psych is a nice demo with a chiptune playing in the background.