All Apple keyboards now come with volume keys, so you can easily increase, decrease and mute the volume. But did you know there is more functionality to these keys.

Holding down the Option key while pressing one of the volume change keys will bring up the Sound System Preference pane. Here you can change the alert sound, alert volume, and when different sound effects are played. You can also change the sound input and output, incase you have an external microphone or speakers.

Holding down the Shift key when pressing the volume keys will disable the sound that is normally played when you change the volume. You can disable this permanently from within the Sound Preference Pane by un-checking the box "Play feedback when volume is changed". Now, when you hold shift it does the opposite, temporarily enabling the volume change sound.

Unfortunately, this one is Leopard only. If you hold down both Option and Shift while pressing the volume keys, you can change the volume more accurately. The entire volume spectrum is divided into 65 instead of the usual 17 (by my count). This means you can adjust the volume by just a tiny amount if it is not quite right.

To disable the startup sound that plays when you turn on your mac, simply hold down the mute button while pressing the power button. Keep it held down for a while, until after the sound would have normally played.