Actully, I clip them onto my ears. Very easy to tailor the soudn that way. True custom acoustics. And the - uh... sensation on the ear certainly hightens ones awarness.
once i tried a ball between speakers - it sure had some effect, stereo was much better but then I moved my head back to the chair, where rest of my body was... and everything just...well, moved back to normal.
Joke aside - the Knutballz gave me a fun idea for some stands that might turn out to be quite attractive, depending on the color of bouncy rubber balls i find