Tile

To assist the sorts of people who would lose their body parts if they weren't attached, Tile is a device designed to be attached to objects you don't want to lose, such as your keychain, so that you can pinpoint their location through a smartphone app. Now, just try not to lose your smartphone.

It would be nice if the Fitbit had a function like this built in... those things are getting lost all the time!

Links

 * Official site