It is reported in one of the article in yahoo news that 5 Careers You Can Start At Any Age are
1) Physical Therapist Assistant
2) Registered Nurse
3) Elementary School Teacher
4) Computer Software Engineer
5) Management Analyst
Somehow I had a feeling this may be right for the traditional way of thought. In the information age a child can learn how to use a computer as young as 10 years old or even younger. Once the child pick up enough vocabulary, he can start
1) To become a blogger - there are so many free blogging platfom out there in the Internet, its a few days of learning and you can start blogging right away.
2) Graphic artist - eventhough the best graphics editing tools right would be the adobe class of suite which is quite dear, there is no stopping one from learning to use free open source tools like komposer (previously known as nvu) for website creation and GIMP for graphics editing.
3) Other niche market are creating digital ecover book for ebook, making video or even selling stuffs on ebay.
The only stopping the young from making an income from this freely available platforms from the Internet though is having a payment processor that allow them to receive money, and one would have to wait till the legal age to have one.