This is probably more for the NW but we had fun taking a radiation detector cruising this year to check levels after the problems in
Japan. We'd take it on hikes and climbing etc....And yes, areas with lower rainfall have lower readings. Next year we'll check Indian Island and Bangor for fun!
On another note, I still prefer paper
charts but if you have computer tech savy
kids get them to set up a
laptop with a
GPS antenna and download the free
charts available for the US. A
GPS antenna cost less than $30......