I have used Delorme Street Atlas on my Toughbook in my SUV for a long time, and one of the features that I had at first wrote off as silly, I discovered was very useful, and I use it regularly now. That feature was what Delorme calls High Contrast Mode.
When you enabled, it turns the background of all the maps to black, instead of white. And it is very useful for night time driving, when you don't want a white screen shining in your eyes.
I imagine from a programmer's perspective this is a real nightmare since I gather the maps are downloaded pictures, and altering them would be a pain in the neck. Perhaps though it could be done in rendering? Some kind of color substitution?
Anyways, I joined the wikidot to throw this request out there.