Mapdroid lets you view maps from OpenStreetMap on your Android smartphone.
You can download a debug build of Mapdroid. It's not perfect, but hopefully it can help you find your way around, or check for missing features in OpenStreetMap.
git clone git://tedp.id.au/git/mapdroid.git
You can contact me on IRC in #osm-au on irc.oftc.net, or email me at ted@tedp.id.au.
Mapdroid is open source. I'll tack on some license headers then it'll be open source for real. The plan: LGPL.
Good times!
— Ted Percival.