MasOSaiX
MacOSaiX 2.1 has been released. It is a free Mac application for creating "mosaic" images.
This is me in 315 porno images.

Pretty simple to use. It takes A LOT of images to finish a mosaic. 50 pictures left me with a bunch of empty gaps. You can save as png with transparency for the gaps, tho, and create more weird effects in editing appliations like GIMP.
You can use a Google image search if you don't have any images floating around on your hard drive. But if you don't have any images to use, you're just plain weird.
You could do some pretty obnoxious shit with this if it did video.
the app takes it's time but it's kinda fun to watch. ok, I am easily amused. It's fun to watch once, maybe.
MacOSaiX and GIMP are both freely distributed. While MacOSaiX is a Mac OSX app, GIMP runs on multiple platforms.