I suppose some of you have heard of this game the surrealist painters used to play -- the Exquisite Corpse (Le cadavre exquis).
The rules are ridiculously simple -- each of the players draws a fragment of the piece (usu. a specific body part) and passes on the sheet of paper to the next person, without the latter being able to see what the previous artist drew.
The point was, at least in their case, to draw a human body, although often times it did not look like a human body.
For some more info see http://www.exquisitecorpse.com/definition.html
So let somebody suggest a format.

Perhaps draw a stick figure where we shall replace the body parts on =]

I think I understand what you mean by taking a look at some examples at the link you gave us. Basically, there can be 3 sections to draw on: the first person draws a head, the next the chest area and arms, the last draws the lower part with the legs and feet. Giving the next artist only the last row of pixels is a great idea. It'll produce some truly wacky images I'm sure but, you'll have to place some limitations I'd think such as colour pallete (b&w?), size, and subject perhaps? I might have a crack at this if some of you are up for it