NextStep used to have a feature where you can install an animated wallpaper. For example, I remember seeing a screensaver being used as a wallpaper (it was starfield). Does this feature still exists?
Under NEXTSTEP/OPENSTEP the program that gives you the background you speak of is BackSpace. I think that FreeSpace took over where it left off, except I'm not sure if it gives you the option of running a module on the desktop. I'm not running OSX, but I think FreeSpace comes with it.
