Zoomable flash animations
It reminds me of one of my grandpa's toys: a tube, printed on the inside (a cartoonish drawing), in which you could slide a shiny sphere (positioned on the tip of a second tube, to hold it).
That spherical mirror created an anamorphosis effect. Sliding it created a zoom effect.
I haven't seen it in a while and couldn't find a picture of it on the web. But from what I remember it started with the same image as it ended with, suggesting recursion.
Btw, more resources on Escher.