John,
  Your message about track ball and ADA requirements seemed like you might be a
little tentative as to whther ADA requirements apply to kiosks with track balls
 etc.?  It is my understanding that ADA applies to interactive kiosks as well
as elevators, and the usual stuff that one might expect it to apply to.  I do
remember some kiosks at the National Gallery of Art that had track balls - they
 were right outside the greek sculpture exhibition a couple of years ago.
      Suzanne Quigley
 P.S.  thanks for the article!  It looks great!