I lost my Fitbit Charge two days ago and tried several Bluetooth-finding apps, including the one made by Fitbit. BLE Scanner was the only one that helped at all. Unfortunately I have to take a star away because the app was inconsistent and the RSSI values were way off. The best one I saw was in the -40s, and when I was actually standing next to the Fitbit it was in the -60s. It did give me an idea of the general area though. Thanks!
Taterinvader about Bluetooth Smart Scanner