YOu can do the Heisman pose, bow, kick the ball into the stands, throw the ball into the stands, dunk the ball over the goal posts... 8 celebrations in all with the following button combos (can't remember what each one does):
L2 + Square
L2 + X
L2 + Circle
L2 + Triangle
R2 + Square
R2 + X
R2 + Circle
R2 + Triangle