The above visualization is by Carolyn Aler and Sam Conway in response to a "Making Sense of the Financial Mess" contest held by Good Magazine in late 2008.
The visualization succeeds in effectively using human abilities to easily distinguish relative magnitude by using simple shape representations of houses to indicate fluctuations in average home price between 1980 and the recent present. I find the outlined circles representing millions of prime vs. sub-prime (credit rating) home owners to be an especially effective tool, because our visual system is very adept at processing differences in color within a pattern. Although difficult to quickly assess exact numbers from such representations, this is besides the point in my opinion -- the general trends in the data are easily recognizable as a result, making deriving meaning from the data a simpler task. The remaining bar and line graph follow similar principles.