From the BBC Dimensions:
"How Many Really? compares the number of people involved in key historical events or situations to the people you know through Facebook or Twitter. You can also add your own numbers — for example, the amount of students in your class.
Choose a story to get started.
Dimensions is an experimental prototype for the BBC. (Find out what happens to your details.) Try How Big Really? to compare the scale of important places and events to the places you know."