Satelite comms. The technology is already on the shelf! Mobile phone operators have spent so much money on terrestrial data solutions that they're holding back to re-coup their money, and are in no rush to miniaturize and roll Satelite phones out, which would bring costs down.
Failing that; USB charging ports in cafe's resteraunts is what I want. I know its not an app, but they would be handy.
An app that can override your SIM lock. Some nice pastry's. Where can I buy a Steamin Weanie Locator?