Figured I'd pull this from something I was reading in my feeds a while back. Hat tip to Sean Michael Ragan at MAKE magazine for posting.
This is not a spiral: "
Slightly off-topic, here, but I see lots of these optical illusion posts on the web, and although some of them are pretty impressive, this one borders on voodoo. I had to run my mouse pointer over the blue traces a few times to persuade myself. [via Neatorama]