I tried the software QLandkarte, what is a graphical application for communicating with Garmin GPS units. It’s main feature (for me at least) is that it can send and receive maps to/from devices. (Its features makes it similar to the Garmin Mapsource)
It was not easy to set it up, because 0.5.2 precompiled from getdeb was unable to send maps (feisty64 package, my system is qutsy64) although, it was working fine for a friend (feisty32 package on gutsy32). Fortunately, there is a source package (0.5.3). But be sure to install its dependencies before compiling it, because the package has no autoconf script. Works great. Its usb-protocol is based on GPSBabel, so the module problem mentioned above can be an issue here too. Can send and recieve routes, tracks, waypoints and maps.