Milkdrop 2 is the best visualizer program I've seen. While iTunes has it's flaws, it's smart playlists are one of the more powerful ways to manage your music.
How can I play my music using iTunes but use Milkdrop 2 for the visualizations?
Milkdrop 2 is a plug-in for WinAmp so I have spent some time playing with the LineIn plugin which works ok but is not ideal because I actually have to use a microphone next to the speakers to get it to work.
I'd like something that directly makes the audio available to WinAmp on the computer.