I downloaded motion x terrain on my I phone 4s it has all major map viewers like google bing and usgs. I played with it out of service and it was a bit slow but always found my location spot on. I was able to save a huge map before exiting service and it worked well you can save waypoints and track routes while out of service wich was neat only downside so far is not showing public or private land and also doesn't show small springs like a topo. I will have to save all destination points on the saved map before leaving the topo at home. For 99 cents it's a pretty cool app so far.It also has options for coordinates when out of service. While my phone said no service I was driving with the cruise set at 75 it called me out at 73.5 I'm impressed with the I phones abilities while out of service. Not sure if droid works the same. I remember trying to use a map on a droid while out of service and it did nothing.