While reminiscing and nostalgia-ing, I remembered the Matrix screen saver, and now I have a hankering to set up some kind of program that would render simulations while I do homework and the like.
First, the nostalgia part: Windows screen savers were pretty dope. I had the "pipes" one for a time, spinning text at another, and the star field was a favorite. My "SSOTY", however, would the maze one. My computer had it, and I couldn't find it on other computers. You could alter some of the parameters - maze complexity, wall/floor textures, walking speed. It was dpe watching the computer meticulously figure out the maze, though sometimes you could see the end goal (a gem or something?) and the computer would alter course and continue mapping the entire place.
Now, the part where you come in: recommend some sims, game or otherwise, that can play in the background. Jeff mentioned some kind of DEFCON game that had a sim component where the world bombs itself. Preferably, something procedural, maybe abstract, but all suggestions are welcome.