I read your blog, and i found the idea behind biz teen interesting, but i think you're targeting a rather small market (the world doesn't have as many young entrepreneurs as it needs).

If you don't mind getting an idea from a complete stranger, why not do a social networking app for people within the same age range but focusing on something that appeals to a wider crowd (parties, traveling[backpacking through the world comes to mind], choosing the right school, etc).

Best of luck.