Stepping into a question, Pete - why not a bar code?
   
A bar code is not hand-countable, not hand-count auditable.  Now we have to
"trust" yet another layer of electronics to translate what I thought I voted
for into a tally and a count.  At the very least, this is another
opportunity for coding error.  Above that, it asks the voter to suspend
skepticism a notch, and trust the technologists.  Worst case scenario: text
says one thing, bar codes say another.
Occams' Rule: keep it simple, stupid!  If it can be done either with a bar
code or without a bar code, then get rid of the bar code!
Pete