I use redpinemapping.
The first time I used a gps for snowmobiling was a couple of weeks ago.
I found that it's almost worthless. It basically tells you if you're on a trail or not. If you say that you want to get gas, it takes you via road like you're driving a car.
I found myself using a map a lot more than the gps. It did however tell me my coordinates and I found out where I was so that I could make it to the actual place I was going.
