> There is enough land to build houses for everybody (maybe a few skyscrapers are needed).

As it happens, I had cause to work this out a week or two ago. Given a global population of 6.7 billion, and an average family size of 4.8 people, each family can have almost 5,500 square feet (which is a fair sized property), before even Texas is filled up.

The old saw (that I think everyone in Britain grew up with) about the entire population of the world being able to stand on the Isle of Wight seems to be false, though; they'd each have a square less than 10 inches to a side.