pretty awesome mac feature :
http://www.apple.com/macosx/features/expose/
not only can you control / scroll through / tile the windows on the desktop by using the 'f' keys but you can also use the desktop to trigger expose features ...
positioning the mouse on the top left corner will 'shrink' the open windows allowing you to pick which you want active.
[img]http://s92915907.onlinehome.us/expose.jpg[/img]