If you haven’t seen Drawball yet, pardon me for being pushy but you should leave here immediately and partake.
It’s a huge social drawing site that allows anyone to draw whatever they want on a massive virtual canvas. Every user is only alloted a certain amount of ‘ink’ per day to prevent any one user from simply taking over, the amount limits you to about 1/10,000th of the surface per day.
However, some sites are getting people to all join in and partake on a campaign to collaboratively generate a logo or some other object of interest. This site also has an animated feature that shows you the site in 40 hour snapshots since it was started, it’s just amazing to watch things appear and get overwritten.