"Sharing policy"? The usual, I guess: give to anyone, but don't get paid or take credit wrongly. I also don't mind if the images are disassembled or modified. They can be posted anywhere, but a nod to this forum would be appropriate (for feedback and requests).
To quote the Finished Maps guidelines:
"We would prefer that maps have an appropriate WIP thread posted in one of the Mapmaking forums and discussed through to finalization before posting your map in here. Alternately, if you have a map that you consider finished, post it here."
I don't suppose this thread could be switched to the Finished Maps forum?
I really like these! I know they're going to come in handy for my pirates...
This is a few years old, but it turns out to be exactly what I was looking for! Thanks for posting this, and take some rep!