Based on some comments on the United States Income Inequality Map, I am posting another United States Income Map, this time showing the Median Household income in the US by Census tract. I created it using a very cool tool: Social Explorer
See also: United States Poverty Map United States Income Inequality Map
Addendum: 8/8/2007 Increased the size of the map legend. 8/19/2007 I added Alaska, Hawaii, and Puerto Rico to the map.