ExtremeTech has an article about the gCensus site, which lets you select US Census tabular data using a web-based interface, and convert it into a Google Earth KML file. Examples include a plot of population density in the Berkeley, CA area:

and a plot showing racial segregation in Philadelphia:

Only data from Summary File 1 is currently available, but the site creator intends to add additional data later on.
Related posts:
- Interactive US Census Data Viewing In Google Earth With The GE-Census Explorer
- Plotting Data In Google Earth Using GE-Graph
- Quick Country Information With The World Gazetteer
- Plotting Swivel Data In Google Maps
- Demographic Maps And Data From Social Explorer
- Urban & Environmental Modeler's Datakit
- Map Surname Densities With The World Names Profiler
- The Global Peace Index Map
- Plot Google Analytics Geographic Data In Google Earth/Maps
- Exporting Shapefiles To Google Earth III – shp2kml
