My idea is to help tourists find their way around an airport quickly without having to ask anyone for assistance.
Considering how many people travel by air every day, often arriving at an airport they have never been to and therefore not knowing the quickest way to whatever facility they require; for example a particular terminal gate, bank, airline office, taxi/bus, check-in counter etc. If there was a small hand held device, similar to a sat nav, that could be picked up and dropped off at any point in the airport, that people could help themselves to and just key in where they need to go (or if it was really advanced their ticket could have a scan bar that the device could read) and the device can direct them instantly. Once they reach their destination the device is just dropped off or can be used to direct them to their next destination. Of course to ensure the device isn't removed from the airport it would have an alarm that could not be switched off if it is removed from the precincts of the airport. The device could be airport specific however universal so all passengers at all airports are familiar with the device and how it works; taking a little stress out of travelling by saving time, worry and missed flights.