Population Summary Map -(dead link removed)
The population summary map allows you to draw a polygon on an area of the United States. What this does is create a 'buffer' line which is sent to ArcServer which then returns the population data for that area to the Google Map. The data is returned as a clickable marker so that you can now view the population data for any block in your chosen area.
The census block data is then processed on the fly to the Google Charts API which generates a 3D pie chart. When you click on the census block polygon a chart is created showing a breakdown of the population by age.
Mapperz makes a big acknowledgement to Andy Gup for creating and making this code available to the GIS community. You can read more about how this map was created at the Mapperz Blog.