Darren:
On the Corsair, they were called Flettner, or booster tabs. When the elevator went up, the tab wnt down. Takes the load off the stick. Something like power steering. I have them on a 1/4 scale Corby Starlett and they are quite effective at taking the load off the servoes. Wouldnt be feasable on anything smaller than a .60 size plane. Corsair has them on ail, elevator and rudder with a trim tab on the left aileron.