Map of the Czech Republic based on OSM data provided by raumbezug
This map of the Czech Republic is based on data from the OpenStreetMap Project. The gmpasupp.img which can be downloaded here can directly uploaded onto you Garmin GPS device. The maps are routable but as they are intended for direct upload onto your GPS they don't come with a Roadtrip or Mapsource installer. However with the help of the MapSetToolkit this limitation can be resolved. The maps are updated quite frequently (daily to weekly depending on the region).
OpenStreetMap works that way, that everybody can upload their GPS tracks from which maps from all over the world are being created. This means that the quality of the map depends on the tracks uploaded by the users (you're welcome to contribute to the project by uploading your tracks as well) and therefore the quality differs greatly from country to country, region to region and city to city. As there are continuously new tracks being contributed the maps are getting better and better every day, so if a map of a region is not as detailed as you had expected either join the community and help by contributing and/or come back in a few weeks or months and you will most likely find a better map with more data and information than there was before.