The Button TrackR
What it is, and what it does: A quarter-sized, Bluetooth-enabled disc that can be tied or stuck to keys/passport/laptop/pets, whose location can be tracked via a dedicated app that tracks up to 10 simultaneously. It crowdsources the location of stolen/lost items out of range by pinging other TrackR users' phones who come near it, then plots the approximate whereabouts on a map.
What sets it apart: It can be set up to sound a loud internal alarm the instant it moves out of range, thwarting potential thieves and serving as a reminder you left it behind
Drawbacks: App can only pick up its location within 100ft
Price: $25 each