"SoilWeb" Gives access to the USDA soil survey information. It uses a GPS reciever to identify soil properties anywhere in the lower 48 states. It can give vital information in the classroom when you are out teaching. This app would be great in an Ag or even science class room.
How it works: It uses your current location to retrieve any and all information about the soil around you. Basically if you can get cell coverage this app can tell you about the soil in the area you are out. All you have to do is ask it to search and it will do the rest.