It would be nice to have some "get new maps" button in the game that downloads new maps from a location where anyone can put maps.
That's mainly because people don't know how to install maps even if they can download them (and because it's easier to do so).
Maps could also have a rating system.
download maps from the game with rating
I noted some more profound thoughts on that topic under:
http://globulation2.org/wiki/Wishlist#Giszmo.27s_Wishes
http://globulation2.org/wiki/Wishlist#Giszmo.27s_Wishes