Maps and a compass, maps (online/offline-"rmaps")
RMaps is an Android app for viewing maps.
Also available at fdroid.
It does rotated maps (compass mode).
It lets you record tracks, export to gpx. frequency?
It also has 'add POI' feature. This isn't direct OSM editing functionality, but it might be useful for recording mapping data. TODO: details. can get the data off the device?