A job gives you more than just money, though. It's a source of experience and helps you to develop more responsability. It also introduces you into the adult world without being too harsh (this also depends on the job).
But the bad thing about trying to find a job as a teenager is that in many places employees are asked for experience which, at this young age, we don't have (at least legally). That is a downer, as well as the fact that not everyone has a driving license or a motorbike (sadly, that's my case, and I can't just say that I have a bike to go to work...). Also, some employers make the most of teenagers' situation with low wages and a lot of working hours.
The most typical summer jobs for a teenager is waiter, working at a camping, a shop, a supermarket... There are also many people who work as babysitters, teachers for children, taking care of or walking dogs... There are many things you can do!
Personally, I like to work in the summer and earn money. I may have too many whims and that's a way to get what I want with my own effort. I'll work as a waitress this summer, I wonder how that will be!