I lost a good 90 minutes to this a few days ago. I really like how he manages to visually express things in a creative way, this is one of his best examples.

Is J.K. Rowling really a billionaire? If so, wtf?

Oops, link: http://xkcd.com/980/huge/

And here's the links:
http://xkcd.com/980/
http://xkcd.com/980/sources/

Yeah, that's a really well-made graphic. I also like this visualization of the US national debt:

http://usdebt.kleptocracy.us/

And yes, J.K. Rowling is a billionaire. She's one of the richest women in the UK.