Something most people (especially in the US) don’t spend a lot of time thinking about is world demographics. I’m sure everyone has heard some variation of the “if there were only 100 people on the planet”, but most might have heard it from second or third hand sources. The website minature-earth.com features a neat video laying out what the planet would look like if there were only 100 people on it. It’s a continuation of the work done by Donella Meadows in 1990. There’s a downloadable version you can use, but it costs money to download (toward the costs of maintaining the site). There’s also a blog, although it doesn’t seem to update often. One bit of irony – you’re going to need a fast connection to view the short video. According to the video, if there were only 100 people on the planet, only 3 of us would get to view the thing anyway.