Volumouse is a useful utility by Nirsoft that allows to change the volume in Windows by simply scrolling the mouse-wheel rather than to click on the system-tray icon of the volume and changing it from there. However it is a bit of over simplification as the software provides a lot of flexibility by allowing to define rules that govern under which conditions scroll-wheel will be used. If the conditions of a rule that you have defined are not met then scroll-wheel will be used as normal in Windows ...