From the U.S. Census:
More than 11,000 people across the country participated in the National Day of Civic Hacking on June 1-2, with many of them using the rich array of local statistics from the U.S. Census Bureau’s American Community Survey to develop new online apps.
One app developed at the event creates heat maps that show American Community Survey statistics at the county level across the United States.
View (and Use) Other Apps Developed Using Census API/Data