A free Mac OS X volume changing utility
Multiple Output Device Control. The Mac OS X 10.5 volume widget works for changing the volume if you only have a single audio device connected to your computer. But what happens when you have multiple audio devices? This is where PTHVolume 2 excels, you can individually control the volume of multiple devices without opening up System Preferences.
Volume Control with Non Apple Keyboards. Your type of keyboard is a very personal choice, if you like the keyboards Apple provides then you can just use the standard volume keys. But what happens if you like the IBM Model M style of keyboards, without custom volume keys. Well PTHVolume 2 comes to your rescue, you can set keyboard shortcuts for any and all volume devices.