I'm new to Mac OS X (just got my MBP a few days ago) and I really like the OS. The idea of full-screening an app or a browser is great, however I wonder where an extra background could be used for, since a full-screen app already uses a new "background". I don't have any programs or maps on the desktop (like on a Windows desktop) since the Dock offers more than enough space for that. So, where do you guys use a second (or third, fourth etc.) background for?