Ecuadortur's routable OSM map of Costa Rica
This map of Costa Rica is based on data from the OpenStreetMap Project. The website is only in Russian, so to navigate it you would have to use google translate or a similar service (unless you speak Russian of course). You can also download additional maps for the OziExplorer as well as tracks from Las Cajas. The maps are routable and come as a gmapsupp.img which you can directly upload to your Garmin GPS Device. If you want to integrate the maps into Mapsource you would have to use 3rd party tools such as the MapSetToolKit. The maps are updated weekly.
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.