Affiliate programs are online earn no invest.
A lot of companies on the web allow you to sell their products and get a commission on the sale.
Paid surveys
Be paid for your opinion! Some companies pay money, some give you gift certificate and some give you the chance to be in a drawing. Unfortunately, most of them are only available for US residents.

Reselling
You can resell service like webhosting or domain names. With reselling you can set your price but you have to take care of the technical support and billing. It’s a good way to start your own little business because you can control everything and your business can easily grow.

Place ads on your site
A lot of programs allow you to make money by placing ads on your site. You can earn money for each or for each impression of the ads.

Starting a scam site
This is NOT the solution! Don’t even think about it.