Normally F11 uses Expose to show the desktop.
Check System Preferences > Expose to check or set what keys are used on your keyboard.
Thanks! I have checked the settings in Expose and it does say F11 return to desktop but when I try it it just lowers the volume.
Actually just set one of the screen corners for "Desktop" (best one is lower right). That way while you are dragging things out of a web page, just drag it lower right and you can then even go to a finder window by hovering over your Mac HDD...
Also, since I don't use full screen windows, I just click a blank space on the desktop that peeks out from behind other windows. Brings up the desktop immediately.