Spot satellite messenger

This is a very cool gadget. Basically a gps, with the particularity that has a couple of buttons, one to check in, so it sends communicates your position, and the second one for help. Same thing but you are asking for help.
The beauty is that works everywhere, not dependent of GSM or mobile networks. It can send emails with your coordinates when you click on the button.

http://findmespot.com/en/