As for the 2x and 3x Monitor setups, I think a lot more people USE those setups, but still just play on one of the monitors, like me.
But gaming full screen on one monitor, while having email, websites, messengers, Skype and maybe an office or other program or three up on the other monitor is something I've been doing for years. Maybe having Outlook (checking for email every 2-3 min), and a interactive web page (lots of flash) open on the other screen WHILE doing the game benchmark on the other would help let people like me see how well the card can handle it. (But yes, I know the limiting factors would be way to many - some general info could be found on how each card runs a game while having to keep things moving on the 2nd and 3rd monitor too.)