I feel like the iPod shuffle or nano might really take off if Apple made them more user friendly for athletes: runners, bikers, walkers, weightlifters etc. I have read a lot of complaints about the shuffle's headphones and how it dies when a little sweat or rain hits it. Right now I use my iPod touch and strap it to my shoulder, but I would much rather use the much smaller shuffle or nano that clips to my shirt if these were more user friendly for sports (heart rate, gps, waterproof or at least resistant, and maybe some other features). The iPhone also has a great app (mapmytracks) that keeps track of speed, elevation, and distance while running. The nano is not bad, but I feel like it is a little pricy for what you are getting. I might wait for the next refresh. What does everyone else use for their running mp3 player?