for a sketch I'm doing I'd really like to play with some balls emanating light beams at arbitrary 3d angles determined by the fft data (pre gotten) of a song using the Minim library (which is awesome, btw)

at the moment its just drawing lame red lines, and looks right awful.

saw this: http://www.garagegames.com/index.php?sec=mg&mod=resource&page=view&qid=4402

and saw amazing results.

So, if anyone's got any advice on simple but realistic light beams (they don't actually have to do any lighting on other objects, just look like displaced light rays themselves) I think this thread would be a good place to put it

(search "Volumetric lights site:http://processing.org" returned no results)

adding to john's reply you can use a cone or a cylinder with a texture that fades to nothing.
or use 2 or more of those objects together.

dont forget about the additive blending or some post processing effect as blur/glow.

that should give you the same results that you have seen t that website