Switcher

Switcher is a free application for WIndows that is similar to MacOSX’s Exposé. What’s interesting about Switcher is the fact that it allows you to not only view the different windows that are up, but they are numbered so that you can control them with your NumberPad (tap the number to go to whatever application for the first nine applications). What’s also a neat feature is the filtering tool that allows you to type in what you’re looking for and the windows automajically are filtered to the keywords you type.
There beats the usual Alt-Tab scenario, and definitely is useful if you’re used to the MacOSX style of sorting your applications.
Requires Windows Vista and Aero.