http://www.youtube.com/watch?v=56gzV0od6DU
http://www.youtube.com/watch?v=aSg2Db3jF_4
I also like how all the Julia sets, when arranged correctly, look like a Mandelbrot set. I made this (https://drive.google.com/file/d/1p8xTxaQmh2c-3t22HTSsggVl_lFjlyv2/view?usp=sharing) a while back (but I've seen better ones elsewhere).
And somebody found a valid game of tic-tac-toe somewhere inside the Mandelbrot. https://www.youtube.com/watch?v=vazwf9A0_ew (https://www.youtube.com/watch?v=vazwf9A0_ew)