This illusion has been around for quite a while and you'll find much better examples on the net, but here's my first (migraine inducing) attempt at doing it with Gimp.

The snakes should appear to revolve, if it's not working try shifting your gaze back up to this text and try not to stare at the picture directly. I'm not totally sure how the effect works but it requires to be viewed with both eyes (try covering one to see the "motion" suddenly stop). Colour selection and overlap is very important when drawing them for it to work also. If anyone knows the exact mechanics and in particular how to choose colours that will work when designing them, give me a shout please.

For me works nicely but i don't think the 4 black dots may help, on the contrary i think they may reduce the effect

That is a fascinating design. It appears to be moving round

Glad it worked for you guys, I'll be doing another one some time and will look better, this was just a trial.

It doesn't seem to move at all for me. Or, maybe, the rest of the universe starts to revolve at precisely the same speed.

Interesting design, though!

It's relative to where you are in time and space Merrak.

Try looking at just ONE black dot.
Pretty neat.

Another cup of coffee and it works for me