Not too long ago, I discussed the use of Alt-Tab to cycle through your open program windows. Using this key combination, a small popup will appear in the middle of the screen showing you an icon for each open window, and allow you to cycle through them. But, there is another key combination which is similar which I thought I would mention here and that is Alt-Esc. Basically, this will also cycle through your open windows, but instead of showing you icons in a popup, it will actually activate each of your open windows as you cycle through.

Once again, how you use this is up to you. Some people use keyboard shortcuts all the time, others rarely. Its all a matter of personal preference.