+ and -: Increase or decrease the intensity (brightness) of the particles; multiple presses further increase or decrease the intensity.
A and S: Add or Subtract particles to the visualizer. You can make the visualizer as complex (or sparse) as you wish.
R: Reset the intensity and particle count to their default values.
E: When in nebula mode (press N), this greatly accentuates the nebula clouds, making them very easy to see. (If you've used the M key to change modes, you may find that the nebula clouds aren't visible; it seems they're only used in certain modes.)
Get Clipmarks - The easiest way to email text, images and videos you find on the web.