OpenStreetMap - OSM
OSM for Garmin: www.OutdoorNavigators.com
The Open Geo-Information Database
Usually maps for GPS devices are available on a commercial base only - to get the topographical cards from all of Europe one would need to spend thousands of Euros. And these maps are protected by copyrights and might thus come with limited installation rights.
At OpenStreetMap volunteers collect "GPS tracks" - track recordings made with GPS devices and load these into the OSM system database, which provides public access.
The collected tracks get converted into maps and the data is then publicly available over the Internet. Variations of the map provided can for example directly be loaded into some GPS devices.
CacheZone supports OpenStreetMap by Logo licensing, donations and organisation of Mapping Events.
Links for OpenStreetMap: