check out this app - "BlueTooth Locator" at the market. it is very simple but it does the job. the app identifies my BlueTooth Devices and whenever I get out of their range it launches the GPS in the background and stores its location. I have a bluetooth car speaker so the app always remembers where I park my car The best thing about it is that it works on its own. unlike other apps where you need to launch them in order to store a location, this app does it automatically.