Aero Shake is an added feature built for fun without anything specific. Just click onto a window shake it a bit well it minimizes all the other window. Shaking the window again will revive all the other windows.
The new user interface of windows 7 make it a lot easier to sift through all the open windows. To maximize a window all one need to do is to drag the window till the top and a neat animation appears indicating that the window is going to occupy the whole screen. To bring it to the original position all one need to do is jst drag it down. This is the Aero Snap feature .Another capability of this feature is that when the window is dragged either to the left or right the window occupies exactly half of the screen.
This is useful for comparison and other features and is especially good on a wide screen monitor.