Well my daughter is 4 so she has no cell or mp3 player. I don't even have an ipod. (Those things are too confusing, I gave it to my bro).
When I was 16, I was allowed to have a cell phone. I think truly, kids should get cellphones on there 16 bday when they start driving. Really thats only when you need cellphones. For emergencys. Unless your really rich, or have a really good cell phone plan.