Dual Monitor Advantage

Okay, I'm a noob about this "dual monitor" thing, can anyone tell me the main advantage of it?

I'm thinking that, is it possible to use one monitor to watch anime (full screen) while I use the other monitor to surf net, chat, watever, etc.? 

>>9
No, it is software that comes with the graphics card, made by the maker of the graphics card, made for the graphics card.
It is not third party.
It would be third party if some random company other then ATI or Nvidia made the software.