Did You Know?: The default Mac OS X (I'm on version 10.4.11) screensaver picture slideshow function can read an alpha channel in a .gif file. That is to say, as the slideshow plays your images, a .gif with an alpha channel will appear to be "on top" of the previous image, and as the slideshow goes on, the .gifs will continue to "layer" on until an image of a different format is displayed, which has a default white or black background.
Take advantage of the randomizing function to create some home-made screensaver machinima art!
The animation above is a sample implementation: The NEW Office Party Screensaver from FATLAB.
In the spirit of Men of the Internet, this screensaver is a series of carefully-sliced 800×600 .gifs, sourced from the faces of the hardest working local board members, regional vice presidents, administrative assistants, and other fruitful regular-dude-generating search terms on the internet. The .gifs layer over one another to hybridize these generic gentlemen into a randomly-generated ultimate budget-balancing force of suits. Its dudes! (< -- math joke)
Click here to download a small .zip file of the .gifs. Point your screensaver to it and set your preferences like this: