I still get a hankering for Picture Consequences. You might know it by a different name, but it's the one you play when you draw a head on a piece of paper, fold it over and pass it on to your mate who draws neck down to belt, they pass it on to someone who does waist down to knees, etc. Draw And Fold Over drags this old parlour game into the virtual world, but with a distinctly analogue feel. Pass your drawing on, share it on Facebook, all that jazz.
UPDATE: Charlie Bayliss just put up a link to Postal Consequences, a website that uploads scans of beautiful snail mail versions of the game: http://www.postalconsequences.com/ - checkacheckacheckitouuuuut.