Lol the pyramids one I saw years ago was in a magazine at my primary school; it was a picture made up of pyramids, but when you went cross-eyed you saw a pyramid, a camel and a palm tree. I loved it so much, because it was the first one I'd ever come across, and I was the only one who could actually see anything. When I returned the magazine, I never found another image like it until a good 5 or 6 years later. ^^
I checked on the link you provided with the guide on how to make 2d into 3d and it is doable. I will learn from that when you create an ASCII stereogram generator i will check it out as well. But i think i can muster something up from ascii, i will try something.