Mac: ProperVOLUME adds more robust sound controls to your menu bar in OS X Mountain Lion, allowing you to switch input and output sources, control volume and check your levels, all from one simple dropdown menu.
In essence, it provides quick access to most of the worthwhile features in the Sound Preferences, just integrated into your menu bar. The app is $2.99 in the App Store (though blog One Thing Well has some promo codes you may want to try out). If you don't feel like dropping, you may alternately want to familiarise yourself with this built-in shortcut: Option-Click OS X's default Sound icon in your menu bar to view an alternate menu from which you can switch input and output devices or open the Sound preferences. It's not quite as handy, but it's also 100 per cent free.