So far Oziexplorer has been ported to Android, and it works very well there. However, there's many Apple devotees who are also offroaders, so what options do they have for an in-car moving map? Quite a few, and here's some of them:
Mud Map
Huge range of maps, ability to upload data into the cloud, lots of features. You can see which maps are available for which area here -> http://www.mud-maps.com/maps