Macs apparently have one volume setting that does not appear on the standard volume menu. It is basically a point in between 0 and 1. To access it, simply click your volume all the way to zero, and then press the mute button. This way, while no lights are lit up, their is still sound coming out of the speakers. Although I could not hear any sound at all with the terrible built-in speakers on my MacBook, my iPod headphones picked up the sound very well. As shown in the picture, the sound is not muted but no volume bars are apparent.
[Via Lifehacker and Macworld]
Technorati Tags: Apple, Hidden Volume, Volume, OS X