QLandkarteGT (GeoTIFF/Garmin map/OSM viewer)

QLandkarte GT is the ultimate outdoor aficionado's tool.  It supports 
GPS maps in GeoTiff format as well as Garmin's img vector map format.

Also it is a front end to the GDAL tools, to make georeferencing 
scanned maps feasible for the normal user.  Compared to similar tools 
like QGis, its target users are more on the consumer side than on the 
scientific one.  QLandkarte GT might not let you select every possible 
feature of the GDAL tools, but it will simplify their use to the demands 
of most users.

See http://sourceforge.net/apps/mediawiki/qlandkartegt/ for details on 
how to install and convert maps.

See http://wiki.openstreetmap.org/wiki/OSM_Map_On_Garmin/Download for
a list of downloadable osm-based mapsets.

This requires geos, proj, and gdal.  gpsd and libdmtx are optional.