I dropped some $$ on these combination earplug/earphones for my Ipod. They are really great, as they reduce the fatigue from listening to the wind noise and I can play the volume way down on the music so that I really just get background tunes. I can't hear speech much with them in, but I can still hear my engine and the road noise of cars coming up and around me. If I'm going to be riding with others I will generally wear some looser fitting earplugs to reduce the windnoise but allow me to hear them talk if necessary at lights/stopsigns/etc.
“Jeezus Snyder...You've always had more horsepower than sense!" -Joe M.