Custom Maps

Never thought I would use custom maps but I was wrong. I can easily findd pdf maps for national parks and state parks. I convert the map with preview to jpg, load it as an overlay in google earth, size and move to get the geodata added and save it as a kmz. All that is left is import into Basecamp. The maps are great for trails, campgrounds, restrooms, etc.

My question is are there web sites to share garmin's custom maps?