I don't know it this would technically work, but here's the situation:
I have a Droid 4 (main phone) and a Droid 2 (DroidTouch).
The Droid 2 has the extended battery, letting me use it for almost 3x as long as the 4, especially when it comes to GPS usage. So, I would like to see if it is possible to somehow run the Droid 2 as my GPS unit in some way (via Droid 4 connection or as standalone if possible)? I don't know how GPS in phones work. I don't see why they couldn't be used as GPS devices without the use of data (see: MotoActv or most GPS watches), but I am assuming it probably doesn't work that way (would be awesome though).
*Both phones are rooted, if that helps.
Edit: I know that I will not be able to stream maps for route navigation. I am interested in this for when i go running/cycling.
I recently backed a kickstarter project called the Pebble Smartwatch and it can receive data from the phone via bluetooth to display different features, one of them being GPS for running/cycling/other sports. While I do not use navigation much, I would use the GPS often and being able to do that with a smartphone not using data would be amazing.