I did try a rather useless device known as an "iJet". It utilizes an IR remote and a piece that receives that signal that plugs into the bottom of your iPhone/iPod. Problem with that device was cables running through my suit and the IR remote didn't work when near metal. I had it velcro'd to my triple clamp, so if i wanted to skip the song I had to take it off the bike while riding and do so. This obviously wasn't the best thing to do mid-ride.
As soon as I saw Apple's introduction of the new iPod Shuffle, I knew I could make a nice stereo for my bike, completely confined to the helmet alone. This system does not need to be removed, except for charging the shuffle, of course. The headphone are extremely comfortable and confined to the inside of the helmet. All you see is a small wire exit the bottom of the helmet with little slack and attach to the shuffle, and the sound is amazing.