Meet Chipolo: a Bluetooth device that lets you track and find your keys, laptop, and other belongings. It is about the size of a coin and only 5mm thin. It is compatible with iOS, Android, and Windows devices. The device has a range of 60 meters. The battery life lasts up to 6 months.
To get started, simply attach the Bluetooth device to anything, and you will be able to find it from your smartphone. You can also use it to make your misplaced phone ring. Costs under $30 at this time.