Julien Notter and Sébastien Vigne of at-elier created this awesome optical-illusion poster inspired by HP Lovecraft:
Now, one would think an op-art Cthulhu would be a lot more appropriate than just a plain ol’ skull, right? But I dare you to stare at this thing for more than a minute without it opening a gateway to unknown, eldritch dimensions of space and time that will suck your mind into its whirling depths of labyrinthine madness.
http://www.ectomo.com/index.php/2007/10/25/cthulhu-cthursday-french-op-art-skull-loves-lovecraft/ (with larger pic - be ware, may open a portal to R'lyeh or somethin')
Did he like mazes, too?