I have some big giant chrome bell on my Breezer that makes a loud "BLING BLONG" sound. Wish I could remember who made it... The guy at the LBS pulled it out of a box from under the front counter when I asked for the biggest bell they sold.
Works great when during the summer the MUPs are packed. This last month its little more than a decoration item as I seem to be the only person who regularly makes use of the MUP...