Not too long ago I heard on the radio about some guy selling official-looking windshield banners that say "THGIR EVOM" so when you come up behind the idiot doing 50 in the left lane, they see "MOVE RIGHT" in their rear-view mirror. Apparently it works fairly well.
I've been thinking about getting one for the Jeep - but the fact that my grill is higher than their trunk, and my assortment of offroad lights all shine quite nicely down into their back window bright enough to give them a sunburn on their neck, seems to do the trick too.
