Actually a lot of gamers have more than one monitor, but only few games supports it in a useful way.
I think D:OS has the potentioal to make use if it. For instance, if you have 2 same sized monitore and you are playing in singleplayer with the characters on different places, then you could use one monitor to show one character.
Or if your secondary monitor is smaller, then there could be placed the inventory and your stats.
I think especially the second option would be really usefull, but at least it would be better than not use the screens.
