There was some confusion regarding what I meant by "offline".

Offline meant off the internet. What I actualy meant, was that I can log my gps coordinates, cool. But I'd love a geographic map app that would be able to display those in a "fog of war" styled map, without internet connection.

I was under the impression that fog of world was collecting users' data. Another user suggested the possibility of opting out. That'd be great. A fully open source android implementation of the concept would be better, but hey, I have work tomorrow...