Hey, great wallpaper!

There are some things I feel could be improved to make this even greater...

1. Easing algorithms for the bars. I feel they are a little too jumpy as they jump too fast to the required level. Easing them could make it look so much better.
2. The volume colors. Those could also use easing as they also feel sudden. Look into JQuery Color. Neat Library that does just that.
3. Changing Opacity of bars or particles, or even bar move speed by the intensity of the music, like the average of all the wavelengths. That would look great ;) (maybe even the color)
4. Background Color changing doesn't seem live. Maybe you aren't checking for it every loop?

I didn't realise audio data was provided through wallpaper engine in the page until I looked through this. I'll be looking forward to trying my own few ;)

Try making a GitHub, I'm sure people would love to contribute.