If you FIND YOURSELF with many workbooks open at the same time, you may be interested in a "hidden" command that will close all workbooks in one fell swoop. The trick is to press <Shift> while you click the File menu. When you do so, the Close command turns into the Close All command. When you select this menu item, Excel will close all of the currently open workbooks. If any of them have not been saved, you'll get the standard prompt asking if you want to save your workbooks.