actually, I read somewhere of someone who rode with a kind of "gutter system" that channeled sweat from his forehead to the sides where it could run off. I know, sounds pretty gross but I saw a picture and you could barely see it, it looked like a narrow tube (think IV-tube) running parallell with his helmet. Except I'm assuming it was just half a tube.

Sorry, no idea if it was attached to a cap, a sweat band or what.