My 7 year old niece got this for her birthday.
Wind up MP3 player. It seems pretty easy to use, an easy drag and drop from the PC, and best of all once charged (mains or USB from PC) you can listen for as long as you like as you can wind it back up once it finally goes flat. This would be ideal for PBP etc as I don't think there's any way on long rides such as that to recharge iPods and other media players withinternal batteries. Oh, this can also charge your mobile phone back up.
If you want a screen + video watching capabilities I see that they've also got
this.