See full-size previews of open windows via taskbar thumbnails

If you’re a Windows Vista veteran, you’re familiar with the taskbar thumbnails feature—hover over an item in the taskbar, and you see a miniature version of that program’s window. (Sometimes the thumbnail is even live-animated, for example if you’re looking at a video window.) In Windows 7, these thumbnail previews are still around, but the new OS takes the preview a big step further, letting you see a full-size preview of the window without “committing” and clicking on it to make it active. That way, you can quickly check info on a buried-but-open window and immediately revert to the window you currently have active. In the sample picture below, we're hovering over the taskbar thumbnail and seeing a preview of the Internet Explorer page circled:

Though it’s easy, it’s not immediately apparent how to do this. Hover your cursor over the program’s taskbar icon, which brings up the thumbnail-size preview. Then move your mouse cursor to hover over the thumbnail preview itself. When you do, the relevant window will come to the fore, and all
others will fade to the background. When you move the cursor off the thumbnail preview, your desktop window arrangement reverts to its previous state. And if you click on the thumbnail preview, you can bring that window to the front.

Incidentally, Windows 7 also lets you close the program window straight from the thumbnail, using the red “x” at upper right or by clicking the center button on your mouse—typically the scroll wheel, if it has one.