Have you tried the new iTunes 8 visualizer? It’s based on Magnetosphere.
And do you know how to access the variations? Start iTunes, start the visualizer, then press the ? key to bring up the menu:
? Toggle help screen
M Change mode
P Change palette
I Display track info
C Toggle auto-cycle (on by default)
F Toggle freeze mode
N Toggle nebula mode
L Toggle camera lock
And some unlisted commands:
+/- Increase or decrease the intensity
A/S Add or substract particles
R Reset particles and intensity
If you find a favorite Mode, press C to stay in that Mode. (Sadly, it won’t stick through an iTunes relaunch.)
Who knows what “camera lock” is? I have no idea.
LED Spectrum Analyzer for iTunes
LED Spectrum Analyzer is old school but I love it.
After you activate it, go to View -> Visualizer -> Options to play around with the settings. I particularly like to check “Choose at random when track changes” under Colours.
Having your iTunes cake and eating it
It’s cool to have pretty moving pictures, but you have to stop the visualizer if you want to choose a different track from your playlist.
So before you start the visualizer, double-click the name of the playlist you want. This will bring up a second iTunes window. In this second window, start playing music, then minimize the window. Now start the visualizer in the original iTunes window!
You can maximize the minimized window when you want to use it as a controller.
Go ye forth and explore the possibilities!