I have to admit to using my ipod on occasion, mostly for long rides on hot days when I need to help to keep going. I use hook-over-the-ear headphones rather than earbuds.

On something of an aside, I don't exactly use music or books. There are podcasts available to a specific # of beats per minute.
These would be good for running, spinning, etc too. They are actually made for runners but are great for cadence when spinning.

At ITunes look for FitPod, Podrunner and there is one more that I'll have to mention later.