What is it? A palm-sized device placed in your luggage which reports its location on arrival at airports.
How it works: The device finds the nearest cellphone towers and reports the airport location by text or email. It's clever enough to enter flight mode before takeoff and activate itself on landing.
How is it powered? Two AA batteries that can last up to two weeks.
Useful or gimmick? It's extra insurance. Reassuring when you land and your baggage isn't waiting for you on the carousel; invaluable in the unlikely event that your luggage is somewhere in Africa when you land at LAX. A downloadable app can be used to identify your luggage on the carousel.
The cost? Around US$60 (including activation fee) and US$13 annual service fee.