Arable Land
If every man, woman and child on earth were given an equal amount of the arable land on earth, how much would each one get?

Answer: Almost 1/2 acre.

Calculation: According to the FAO, there are 1,380,515,000 hectares of arable land on earth. There are 2.471 acres in a hectare, so there are 1,380,515,000 x 2.471 = 3,411,252,565 acres of arable land on the earth. The population of the earth (from my "People Calculator") is 6,959,420,814 (at least it was on 9/2/11). Therefore, every person gets 3,411,252,565 / 6,959,420,814 = 0.49 acres.