Appfrica has a great infographic that looks at the number of Earth's dead humans and the causes of their deaths, and creates comparisons between the population of the dead and that of the living.
"How many people have ever lived?" The numbers in this piece are highly speculative but are as accurate as modern science allows. It's widely accepted that prior to 2002 there had been somewhere between 106 and 140 billion homo sapiens born to the world.
One interesting fact he digs up: There are more people currently alive in Asia, Africa and Latin America than the total number of people who died—anywhere, and for any reason—during the entire 20th century.
Appfrica: Population of the Dead
(Thanks, Maria Popova!)