There's a device out there in the wild called the HTC Fetch. While we're seeing places like Clove put the device up as "coming soon" already, even they don't have full details on what this device does, exactly. If that seems strange to you, you'll be surprised at how ravenous modern day early adopters can be.
This device is quite likely set to be coming up as an answer to "Tile" and will act quite similar to what we've seen come out of the Nokia Treasure Tag. Tile (and the Treasure Tag) connect with your smartphone with a simple NFC bump and can be tracked with Bluetooth.
What we're expecting this HTC Fetch device to do is the same thing - working with a built-in (possibly rechargeable) battery, HTC's solution will connect with devices like the HTC One then show up on a map in a unique app we've not yet had the pleasure of looking at. It's also possible that this tag will work with Windows Phone devices like the HTC Windows Phone 8X.
While we're waiting - think about how far the range is on Bluetooth: 100 meters in normal mode or 50 meters if you're using Bluetooth LE. Bluetooth Low Energy allows your smartphone to keep Bluetooth on and seeking at a far lower power requirement than in any past iteration of the technology - just so long as you've got Bluetooth 4.0, of course.
Expect HTC Fetch to be appearing inside the next couple of months, with a price ringing in at around $40 USD. Stick around as we actually get the device in to take a peek at it ourselves, too - keys be found!