Free GPS maps for Garmin MapSource

I discovered this amazing service the other day, I was aware of the OpenStreetMap project, user contributed global street maps, but I was unaware of the additional service which allowed you to download maps to be used on Garmin devices, including MapSource. Whilst Garmin produces some very comprehensive country maps, they miss some of the rarer countries, which OpenStreetMap have covered.

Central Asia free Garmin MapSource map