A.W.
Oh boy, you are not alone. My son will slam his head against the wall, and punch himself in the face(he is 2 as well). I think this is seriously just his way of throwing a fit and trying to test your resolve. And, it's actually a really smart thing for them to do. Because they know that you don't want them to be hurt, so they will get a response.
My advice would be to put him in the safest place possible, keep his nails trimmed, and TOTALLY IGNORE HIM. I know that sounds harsh, but what he is looking for is a response from you of any sort so he can feel like he has some control over his situation. Let him know it won't be tolerated. That seems to have helped ours immensely. (FYI- if the fit happens outside of the home, I leave, put my son in his carseat, and stand outside of the car. That way you don't get a headache from the screams, he's strapped in so he can't do much damage, and he's not getting a response from you)
good luck!