In-case link:
http://youtube.com/watch?v=ipzR9bhei_o I just ran across this really neat video of Bach's Toccata & Fugue in D minor. [8:34]
Click to view
What I find fascinating about it is not so much the actual technique used, although that's cool too. What I love is that this lets you see all those neat patterns that Bach was so good with -- inversions of the theme, in particular, are a lot easier to notice. Plus, you can see chord changes getting ready to happen, at the same time as your Western-music-trained auditory cortex can hear them getting ready to happen. Woo cognitive consonance.
(I don't know enough about organs to know what the different colors stand for -- different stops?)
EDIT: Oh, and, after you watch it, it looks like your screen is shifting to the right. Hee.
The audio for the above is a MIDI -- admittedly a good one -- but I guess that's an unfortunate requirement of the software that makes the visualization. A more traditional rendition:
http://youtube.com/watch?v=_FXoyr_FyFw