Thought of this one an hour ago; this one might actually work. I haven't seen it around anywhere but here it goes - feel free to give any and all suggestions: A protective case with a chip inside. It charges just like any other battery case, but it's not a battery case, it's a lost phone type of device. Directed towards people who are suseptible to losing their phone or something. Location services are always enabled and something (haven't figured this part out yet) would be needed to take the case off. Just like "Find My iPhone", it would connect to a server and you'd enter credentials you set on the phone when you first get the case. Thus, phone found. The only flaw would be when the case dies, but since it wouldn't need much power consumption, it would last a while. So, what do ya think?