I think Michigan State's 1952 national championship in football was undisputed.
For what it's worth, I did mention that the only criteria I was using for football was either the AP or the coaches poll (UPI until 1990, USA Today starting in 1991). Those give you the following:
Stanford (football 1926, basketball 1942)
Cal (football 1920, basketball 1959)
Ohio State (football 1942, 54, 57, 68, 2002, basketball 1960)
UCLA (football 1954, basketball 1964, 65, 67-73, 75, 95)
Michigan State (football 1952, 65, basketball 1979, 2000)
Michigan (football 1901, 02, 32, 33, 48, 97, basketball 1989)
Maryland (football 1953, basketball 2002)
Syracuse (football 1959, basketball 2003)
Fl*rida (football 1996, basketball 2006)
Arkansas has never won a football championship from either poll. That 1964 "championship" was awarded to Bama in both of the aforementioned polls.
I also realized that prior to 1936, neither poll existed. I used this site:
http://homepages.cae.wisc.edu/~dwilson/r...champs.txt
to list the ones prior to 1936.
USFFan