Much like Mac OS X's Dashboard, which contains Widgets, Windows 7 has developed their own uniqued version, which they call Gadgets. This quick tip video from Microsoft will help you understand where and what Gadgets are, and how to use them to best suit your needs.
Gadgets put information and fun—like news, pictures, games, and the phases of the moon—right on your desktop.
In Windows Vista, gadgets were corralled in the Sidebar. Windows 7 sets them free on the screen, where you can move and resize them as you like.
Drag a gadget close to the edge of the desktop—or another gadget—and watch it snap neatly into place for a streamlined look. Open windows getting in the way of your gadgets? Use Peek to make them instantly reappear.