Aero Peek or Desktop Preview is a new feature in Windows 7 which lets you preview the desktop, making the the windows on top transparent. This tutorial will show you how to enable the Aero Peek or Desktop Preview.
Related Tutorials:
How to Disable the Desktop Preview in Windows 7
Minimize Windows By Shaking a Window in Windows 7
Maximize a Window in Windows 7
Aero Peek/Desktop Preview example:
Right click the extreme right side of the Taskbar >> Check the Peek at desktop option.
Aero peak will now be enabled.