Berkley, California
Pasadena, California
Somewhere in the San Bernadino Mountains, California
http://www.shirleyjones.com/Archive/doodah/doodah.htm
Kalamazoo, Michigan
Moorhead, Minnesota
Juan's link Ocean City, New Jersey
Columbus, Ohio
http://www.marshallmcpeek.com/news/doodah/index.shtml

There are probably more...

Check out this link, folks! I particularly liked the idea of the International Water Tasting Competition in Berkely, West Virginia and the Mashed Potato Wrestling and Potato Days in Clark, South Dakota
http://www.eccentricamerica.com/whos_who.htm