I understand the concept and the power behind putting Geiger counters in the hands of just about anyone and then aggregrating the info online, although I think this just might be a case where just because you can doesn't mean that you should do it.

Granted, there is definitely a lack of radiation data out there, but taking valid, accurate readings across all these users is not as simple as you'd think. Inaccurate data can be just as bad as lack of data, whether for the online collaboration or just for yourself.

This article lays out some of the complexities of using a Geiger counter.