I'm currently working on a solution that is able to draw offline maps based on OpenStreetMap data. The map drawing code is advanced and likely needs more performance tuning and some improvements regarding the drawing itself (the map could simply look a little bit nicer).

The code is in C++ and draw into a cairo surface. While it currently is a binary it could be factored out into a library. If anybody is intersted in participating. I can definitely need some help to get this done in reasonable time.

Note that there is currently also Navit for map darwing and routing with similar aproach and libchamplain for map drawing only.

I also recently added some code to support route tracking and KML export to GPSJinni (extras-devel), which could also need some help...