I made a wind deflector for my wipers. Ok actually i took my old fish-tank lid and strapped it to my car.
It looks like it should be pretty aerodynamic compared to the wipers sticking up catching wind, but i don't have a wind tunnel so..
It's a piece of coroplast with steel wire fed thru it, then hooked into my car and closed in the hood gasket. Been on my car for a few days and I've tested it up to 75mph with wipers on high.