I'm sure most of you have seen the Spanish Castle Color Illusion:

http://www.johnsadowski.com/big_spanish_castle.php

Well now its creator, John Sadowski, has posted a tutorial showing how to make your own color illusions using PhotoShop:

http://www.johnsadowski.com/color_illusion_tutorial.html

I've done my own using a photo of me in pirate costume (wearing a Doug Higley Walk-Around Dark Museum necklace!), and it's a lot of fun:

http://airship.home.mchsi.com/pirate.htm

Love that expression! PRICELESS!!!