Created by stoner-geeks for stoner-geeks, a visualization studio is a computer program whose main function in life is, like most other computer programs, to display lots of pretty colors.  Unlike these other programs, visualization studios claim to do this to music.  In theory, they use sophisticated beat detection and amplitude rendering algorithms to make what happens on-screen match what happens in the music.  In practice, one often has to be stoned beyond belief before it seems like these algorithms actually work.

Most modern visualization studios are plug-ins for full-featured mp3 players like XMMS or WinAmp.  Arguably the best one kicking around now is integrated into Apple's iTunes.

What's actually interesting about these programs is that they were written with the obvious intent of helping LSD or pot users get their rocks off, but have become so pervasive that they are now culturally accepted enough to be packaged with a product from an industry titan.  In this way they are kind of an inverse glowstick, since those particular bits of chemical filled plastic were originally often used to keep kids safe during Halloween and are now a favorite of ravers looking for some extra stimulation.