[Jeff Rodriguez]

If I remember correctly, a team in the past few years has done this. They put small LEDs on the sides of their safety glasses. When the LEDs went on, the driver could see the light with his peripheral vision. It was pretty neat.
I don't know what team it was, or if they continue to do it.
I also think having a cord hanging from your glasses/hat/whatever would be annoying when you turn your head quickly.