Blue Balls Machine
Writing about web page http://blueballfixed.ytmnd.com/
The Blue Balls Machine is a wonderful Rube Goldberg contraption that serves no purpose except to move, well, blue balls from one place to another. It's not a game, and not exactly a work of art; I don't know what I'd call it, exactly, except that it's mesmerising.
A quick look at how it's done reveals that the whole thing is one large (2.4MB) animated GIF, which is impressive enough by itself, but it's even more impressive when you realise that (a) it tiles (try resizing your browser window as big as it will go), and (b) the movement of the balls wraps around the image like asteriods in the old arcade game. The effect is to make a seamless, infinitely big machine, and if you can look long and close enough to see where every ball starts and ends up, then I don't believe you. (Pop quiz: how many balls are there?)