I would dearly love to have some use of my second monitor in game. Before the days of GPS many drivers mastered the ability of driving and reading a map so it's not really that unrealistic.
For those who worry about the advantage it gives, make it cursor active, so that the screen your not on fades somewhat. Keep the chat, team, and other functions that clutter your main screen easily viewable, but let the active elements of the map fade enough to take away some advantage.