Everyone has their favorite. I like Fugawi. It comes with a base map
and has the capability to scan in maps and create your own digital map.
then you can download this map into a Palm with GPS and then you have
a nice map personalized for boating or hiking. I wasted untold hours
playing with this thing.

Fugawi also has a free enc map viewer. These are maps put out by the
gov't that show waterways, obstructions, hazards etc. Nice too.

Have fun.

Don