lol. i always have run dual monitors ever since i have figured out how. i usually game on my left one, and have wmp and my temps open in the other (along with myspaceim, msn, yahoo, and task manager)
what i think would be pretty cool, say for instance a game like halo, you have one monitor as your main / front view, and you have another monitor that will look behind you or show little windows with different views of your body or something. kinda like flight sim x
supreme commander can utilize two monitors, its useful because u can leave one screen at ur base to watch for attacks and do other stuff in the other screen.