And, at the other extreme to my last post, possibly the worst data visualisation I've ever seen. As I put it at work: "If Edward Tufte were dead, we could hook magnets up to him and power a data center from the rotational velocity of his corpse right now."
I'm genuinely not sure whether the x-axis or y-axis is a more horrifying affront to the art of visualisation.
(note that the source article now has a new graph, and an update: "An earlier version of the infographic in this story presented the StackOverflow data in a confusing and conceptually problematic fashion." Yes, you could say that...)