There is an incredible visualization in winamp called MilkDrop. I use MilkDrop 1.04b. To select it rightclick on your equilizer and go to visualizations and then Select Plug-in. From there select Milkdrop and start it up, use full screen to get the full effects.
I'm not sure if everyone has this visualization because I have the full version of the newest winamp that I paid for (COUGH COUGH COUGH COUGH COUGH COUGH COUGH COUGH COUGH COUGH COUGH COUGH COUGH COUGH COUGH!!!!).
Still though I could watch this trippy visualization for years while my favorite music plays in the background and bends it to it's whim. I dunno if everyone already knew about this but it's seriously cool.
I have Nulsoft Winamp Pro version 5.0