By far, Apple makes the best MP3 players. The iPod Nano and iPod Shuffle are great for running and biking, however, make sure you purchase a service contract. They both will die eventually due to sweat or humidity. The table below gives you links to these two players along with a few advantages and disadvantages of each.
Ipod Shuffle
Ipod Nano
Advantages:
CAN BE OPERATED WITHOUT LOOKING!!!
Tiny
Light
Clips on to clothing very well
Playlists
Voice can tell you what song is playing
Inexpensiv
Advantages:
Small
Fairly Light
Touch Screen shows you information
Playlists
Built-In FM Radio!
Can be used as a Wrist Watch!
Disadvantages:
Susceptible to Failure due to moisture
Disadvantages:
Susceptible to Failure due to moisture
Can't change songs or playlist wihtout looking
Difficult to use touch screen with gloves on
Expensive
Cool Accessory: IWatchz Wrist Watch Band for Ipod Nano