I actually set the noise limiter on my iPod to "as loud as I think is good for my ears in a normal environment" before starting the bike once, just to prevent myself from cranking the thing on the highway and not realizing it. The reduced wind noise actually lets you year your engine and other traffic better, in my opinion.
I agree with the others about not using in city driving, though. I will sometimes have them in my ears but never any music until I hit the county roads.
