To understand how a knuckleball works, it helps to have a basic familiarity with Bernoulli’s principle, the Magnus effect, and the Prandtl boundary-layer theory, for a start.{Thanks Carrie.}
I should add that in high school I had a math teacher who tried to convince me to throw the knuckler. I've often dreamt of what might have been if I had taken his advice.
{UPDATE 3:25pm: Oops - I forgot the link to the New Yorker article on the Knuckleball.}
