Skobbler uses OpenStreetMap data for some time in their offline map and navigation apps [1]. They charge a small amount per region download for offline use. I haven't used it for some time but recommended it to a friend who likes it.

A bug tracker for OSM data also exists [2].

[1]: http://www.skobbler.us/info-contact/company-team [2]: http://www.skobbler.us/mapdust