This example takes data from the US Census in the form of shape codes and population, massages it into a merged GeoJSON file, and then overlays it on to a Google Map. Specifically, I wanted to look at the population density of Portland, Oregon with granularity down to the block group.
The unimaginatively named “hoodRise” tool was created to allow one to find unique and awesome views of sunrise / moonrise events over Mt. Hood. The user is free to choose any location using a Google Map and the tool will determine the best days over the next year for these events. Here is an example choosing a location near the Sandy River on the Ramona Falls trail: