While yes, this may be on a much smaller scale that Mark (Facebook CEO) did, but everything starts somewhere. Nathan (now 18) and Andy (18) began a lawn and window service a year ago. Doesn't sound too exciting?
Just take a look at their website - AN Window and Lawn
Their website is better designed than a lot of websites that I have seen by adults. It's one thing to start a business - it's another to have a web presence that grows your business to something that makes money and helps you gain clients.