If you follow me on Twitter, you know already how much I love the xkcd series. (read about it in Wikipedia). It's my personal healthy, regular dose of smart, geeky humor.
The cartoon on the left is the latest published. It's the most effective attack against dumb, shallow, trivial infoposters I've seen. As I've explained in the past, I don't call those things "infographics" anymore, as the world "infographic" has a long and noble history in the news that the graphics xkcd mocks either ignore or disrespect.
I'm not the only one to say this, of course; Connie Malamed agrees. So does Jesús Díaz. And Stephen Few —see also a few minutes of his talk at Malofiej 2011, about decoration and substance. However, nothing I or others have written or said (1, 2) is as powerful and persuasive as this visual satire.
xkcd has also ironized about statistics, design, and cartography. Here you have some favorite cartoons of mine:
• Choropoleth/dot maps that are just population maps
• Map projections
• Stupid charts
• Correlation and causation
• Significance (for journalists!)
• Conditional risk
• Frequentists vs Bayesians (it's hard to get geekier than this)
• Spurious co-variation
• The null hypothesis
• Data-driven dating prospects
• Precedents aren't good as basis for predictions
• Kerning and Papyrus
And here's the xkcd website.