Hans Rosling is one of the best known practicioners of of data visualization. In his most famous lecture, he plots 200 countries over 200 years using 120,000 numbers. This entails plotting life expectancy against income for every country since 1810. Each bubble's size represents a country's population size. By having the plots scroll through each consective year, he shows the progress in which the world has made in becoming "less sick" and "more wealthy".

An example of his lecture can be found here:
Youtube Link