Usually, when I travel, I always carry-on. However, with the price of airport luggage check-in, I have found that the only time that I check-in is when the airline will do it for free during that critical moment when I get on the plane.
The Wireless Luggage Finder is designed to combat the problem of finding your bag at the baggage claim. All you need to do is clip that credit card sized thing and turn it on. After your flight, you turn on the round keychain that you see there, and it will sound when your suitcase is within 90 feet. So when the suitcase rolls onto the luggage carousel, you will hear a beeping sound on the keys.
It has an individual code so there is no mistaken identity. You can also use this device as a way to find your keys. In that case, just take that credit card device and turn it on. Assuming the keychain is on, then the beep should give away the position of your keys.
Personally, I would have made this device so that the credit card shaped device will beep, as that would give away the position of my luggage. However, that would defeat the purpose of using it as a key-finder. I guess you have to sacrifice one for the other.
Anyway, you should be able to pick it up at the X-treme Geek site for about $24.95.