AudioSpectrum is a screensaver that responds to surrounding sound. Formerly known as AudioParticle and AudioPartiColor.
Using audiospectrum is pretty straightforward. You need to create a folder called "Screen Savers" in your ~/Library folder and drop the file in it. Once this is done, it will be readily available in ScreenSavers preference pane. Do note that if you're using a PowerMac or another computer without a built-in microphone, you'll have to change your default input in the Sound Preference Pane. This ensures that the screensaver can detect sound. But if you still have trouble, feel free to email me or leave a comment, and I'll provide you with a version that monitors the line-in.
In the latest version, I've separated the audio spectrum into low, mid, and high bands. Each band's color depends on its relative strength, making it quite fascinating. It's also responsive, so you'll have a great time experiencing it.
Version 1.2: N/A