There's two types. Mass balances that work like Lou suggested and aerodynamic balances that help ease the stick forces by providing a certain amount of area ahead of the hinge line. The ears on the old Fokker WW1 aircraft come to mind. And then there's this classic example of the Piper Cub with it's aerodynamicly balanced rudder...



As Paul suggested the forward area eases the loads on the controls to the pilot.