SPOT:
SPOT SATELLITE MESSENGER :: HOME PAGE
Basically a satellite based limited communications device and tracker. It has an emergency button like an emergency rescue beacon as well as a limited capability to send messages. Also allows a third party to track the user. Delorme developed it and Garmin bought them apparently to get that part of the business. They might get better maps that way too. ;-) They are scene more in back country publications but perfectly reasonable in any RV type usage as long as they can get to the satellites more or less like a GPS does.