thisispastpresent and The future
Decent substitute for BTC This is a good and fast app, much faster than some similar ones. Although it has just a map view function (without POI edits or GPS tracking/logs), it's simple, so if you want a relatively small app just for browsing OSM to explore places around you, this is a good choice. And I like the availability of several map styles (along Mapnik) like the OpenCycleMap or the Public Transport map.
Mapnik tiles have stopped loading In the last couple of days.
Nice For the region I'm working with OSM is more detailed than Google
Very cool APP. Shows way more small hidden places than gmaps