Right now the fog of war, for players, is a black void. This is functional and makes sense, but can be jarring for the players with just how sheer the black appears. A textured background would help the players remain focused and engaged. I think it could be further enhanced if the GM could select some images that would be greyed out. So if the party is in a forest, a generic forest texture would appear. As the real map is revealed, the sense of tension or interest could be fostered as unexpected features appear.
Further, right now the tools for revealing the fog of war are limited to rectangles. This works fairly well if the grid is squares, but poorly for hexes. Would it be possible to add a section tool where one could drag and reveal the grid squares or hexes that were selected? Thus, the GM could much more easily reveal a specific area based on the map grid?
I think this would help atmosphere and flow greatly and would increase game flow.