New in Windows 7, Peek gives you the power of X-ray vision, so you can peer past all your open windows straight to the Windows 7 desktop. Simply move your mouse over the little transparent rectangle in the lower right corner of your screen—and watch open windows instantly turn transparent, revealing all your hidden icons and gadgets. That’s a fast way to find files on your desktop, or get a peek at the latest traffic report.
If, however, you don’t want to use Aero Peek or if you find yourself accidentally activating it when your mouse works it way in to the bottom right corner of your screen, you can easily disable (and enable) it again.