Windows Vista (with Taskbar Shuffle) makes it easy to close programs by middle-clicking their taskbar button. In Windows 7, middle-clicking a taskbar button opens a new program instance. The easy-close solution? Middle-click its preview window.

That discovery comes from Lifehacker reader Felipe, and it adds even more elegant usefulness to the Windows 7 taskbar, and the Aero Peek feature in particular. Whether or not you have the Aero Peek
preview windows enabled, hover over a program icon on the taskbar, and
when the window list pops up, you don’t have to mouse over and hit that
tiny little "X," just middle-click to wipe it away.

What if you lack for a middle mouse button, or you’re using a
trackpad with an inconveniently located middle button? Felipe’s got you

You can configure a corner of the touchpad to act as a
middle-click button. Just navigate to the advanced settings of your
touchpad (type "Mouse" in the Start menu search box) and turn this
feature on.