Windows 7's new 'snap' feature

Windows 7's new "snap" feature makes it easy to dock open applications on either edge of your computer monitor. Just grab a running application by the title bar and drag it toward the left or right edge of the screen.
As you get close to the edge, you'll see a translucent rectangle surrounding half of the screen. Release your mouse button at that point to see the application automatically stick to the edge you're approaching.