OpenFietsMap is a free routable cycling map of Belgium, the Netherlands and Luxemburg (Benelux) for Mapsource/Garmin GPS units.
The map is based on data from OpenStreetMap and published under CCBYSA 2.0 license; OpenStreetMap creates and provides free geographic data such as street maps to anyone who wants them.
The site is kept up to date: Latest map May 21st, 2011 both for:
Windows installer for Mapsource and gmapsupp.img to install the map directly on the GPS/SD card*)
Mac gmapi version for Road Trip/Mac