see osmand, locus, oruxmaps. i like locus because it handles THOUSANDS of tracks and TENS OF THOUSANDS of waypoints very easily. no more plugging in to the computer to transfer ONE RIDE and then having to make room/etc afterwords. also, you have OFFLINE ROUTE BUILDING with locus (via the brouter app) that means when you find a bridge out you can build a route around it in seconds. gpx / kmz / kml and a lot more gps file types are supported by locus. you can also convert (export) to other file types with locus. check out the locus thread, it's long but very thorough.