So after the t-shirts and other armbands for your Ipod, here is the cap for running to music: the ISoundCap


You insert your Ipod (nano or shuffle) to the back of the cap and then you can run, go bike-riding or your favorite sport free of all movement and to music!
It costs $29.95 and it exists in several colors. You can buy it from here .
As you can see the combination of sport and music is making  a big noise : -)