My practical solution is to start calling targeting on the ball carriers. If a defensive player is going low, and the ball carrier ducks his head down, that's more on the ball carrier than the defender.

My impractical solution is that maybe Joe Paterno was onto something when he suggested getting rid of helmets. How much have the better helmets reduced head injuries? I think they give false confidence to players. Take away the helmet and they'll be much more careful.