One good way for teenagers to break into a job is to start contributing to an open source project. Many in the community are old hands in a variety of different companies and organizations. They can open doors for you.

Also, try tapping into the resources around USACO. Rob and the others have many links, and many USACO alums have become quite prominent. Some really like to help young people out.

Rent A Coder and TopCoder design and development, eLance, and others, are all pretty much a waste of time. They are a market for lemons. You can learn far more in different environments.

The ideal situation? You're given a project with an enormous jump in responsibility, you get to work on something interesting and challenging, you get to work with people you can really learn from, and you get to see a project you're proud of through to completion.

If you'd like to, feel free to contact me -- details are in my user profile.