I was perusing your site, came across your page investigating showing periodic data on a circular graph and it reminded me of a style of spectrogram I was interested in exploring, one which makes the representation of harmonics more accessible (for me anyway).
Since I started my visualisation work I have been curious about the many different ways of showing spectrographic content. I'm not sure if the following idea already exists, I was hoping that maybe yourself (assuming you can code) or one of your work colleagues could easily knock up a version of this if it didn't.
The idea is that the spiral represents the non linear frequency relationships where, as shown in this awfully crude picture, each harmonic of any series of frequencies exists at the same angular position (which can be colour coded). I would love to see this if it already exists. If you know of other systems, let me know, the more the better.