I guess the most striking feature of the Windows 7 OS is Shake It... Let's see why?
Suppose, you have 7 or 8 windows of different applications open at a time on your machine. And you want to concentrate on a single window and work in it. Just click the title bar of that window, keep the left mouse button pressed, and just shake your mouse. Presto! All other windows will disappear. When you are done with your work in that particular window, again shake it. All the other windows will be displayed on the screen again!
Cheers!