What is a free and best way to make money online for teens?

hi there are many ways to make money online.. here are a few:

Pay To Click (PTC) or Pay To Read (PTR).
These are websites that pays you for clicking or viewing online ads. All you need to do is to click on the ad and wait for the countdown timer to finish its countdown before you can claim credit for these ads. Credits ranges from $0.001 to $0.01 per ad. For PTCs, Ads are viewed on the PTC website while PTRs send the ads through E-Mail to your inbox.

Paid Surveys
These programs pay you to answer survey questions. Amount of payment depends on the difficulty and length of the survey. The more lengthy or difficult the survey, the higher the payout per survey.

Affiliate Marketing
This is one of the most popular form of business online. It involves partnering a product company and helping them to market their product through your own website. This form of marketing is commission based with no basic salary.

Pay to Write/Blog
These websites pay you to write articles for them. Articles are either publishes on these pay to write websites or on your own blog. Payment can be based on number of views on your articles, to a percentage of advertising revenue that your articles have helped to generate or a fix sum for your article.

Advertising
The fifth and last type of online moneymaking program is also about advertising. If you have got a popular web page that has high traffic flow daily it will be a good idea to help companies to advertise their products or websites on your web page. Or a popular method is to use Google Adsense to help generate extra revenue for you.

I will suggest that you build a blog maintain it and generate decent revenue from your blog. This is probably one of the better ways for a 13-17 yr old.
here is a site that talks abt 7 ways of generating good revenue from your blog: http://zooble.blogspot.com/2007/12/generate-income-from-your-blog.html

all the best in making money online =)