Update: My good friend Paul pointed out that this site produces pop-up spam windows. I didn't get those because I use the wonderful Adblock Firefox plugin, so if you're concerned about such things, please don't click on the link.
People reckon that fair dinkum artificial intelligence is still a long way off, but I suggest to you it is with us right now!
Witness the Mystical Ball.
Of course, it's a very simple trick, but try pointing a few people to that site. I'm sure more than a couple of them will be amazed for at least a short while :-).