Kalin of the Safecast organization has been working hard at building data maps from measurements taken by their mobile data collectors. The current map set includes over a million data points, and even has a few background measurements in various places around the world to serve as a comparison. These baseline measurements were taken with the same hardware that Safecast normally drives around Japan with, so there should be no adjustments needed due to differing equipment.
The winning entry is from HackerSpace Charlotte, and it is FANTASTIC. I totally agree with the panel on this one. The other entries were incredible, but this one hit all my own visions of good educational gear:
1: Its BIG and easy to see, easy to relate to what is in their book