I've thought about putting this on my keys in case they are stolen.
Much better to leave them anonymous and just get a new one cut for a few dollars (as opposed to needing to replace all the locks if your address is identifiable from they key and it doesn't get returned).
But I personally love my bluetooth tracker...and they finally made one that takes replaceable coin cells!
linky link ?
Albertson's at least had this policy in 2004, with some details from an employee: http://www.goodexperience.com/tib/archives/2004/06/albertson...
I think he still has that metal tag on his keyring.
It's never been tested, but I like to think it works!