I nicked this from a mailing list I'm on:

On Aphex Twin's Windowlicker EP, the second song [Formula], when played through some sort of wave display unit, actually makes pictures...wow...most songs look like random fuzz running across the screen, but this one really was tracked with the thought of it visually representing something. Honestly visual sound, no bullshit. that is ...WHOA....here is one of the best pictures from the track: http://www.iki.fi/jjn/aphex.gif

I have no idea if this is true. I seriously hope it is, though. Perhaps if you have 'some sort of wave display unit' you can confirm this?