ooh - I love the letters idea.
we do that at footballs game - hold up a big "D" and a little "fence" (i.e. a picket fence cut out from a white posterboard.
advantages:
* the letters can be big & won't block much of the view behind them because they aren't solid (you can see thru a C, H, A, !)
* 4 people get to hold something
and CHA! is for everyone! one CHA is enough for all of us!
(not enough for stingo but go figure....)