Not really the focus of the article, but I think that /r/place was a neat idea, but hard to produce much with.
I feel like maybe there are forms of collaborative art that might go further, like letting people propose various changes to a chunk of pixels on an artwork and letting people vote on the changes.
I mean, that visualizes the changes, but what I'm saying is that I think that it'd be possible to go further with collaborative art than having a one-pixel-per-person cooldown.