Swirly Tattoo-effect - Anyone know a good tutorial

I have seen this effect on a number of sites now and I absolutely love it, but I can’t figure out how to do it myself.

E.g.1 lemonaise.com (just posted in the showcase and critiques section)
E.g.2 bolermountain.com

Does anyone know a good tutorial on the subject of “tattooing” my flash pages in a drawn-in revealed style??

Thanks a bunch! :hoser: