ADF.LY
What is adf.ly?
Adf.ly is a free URL shortener service that allows you to earn money by sharing your links.
How does it work?
When you shorten a link using adf.ly they create a 'redirect' url, when somebody clicks your link/s an ad is displayed for 5 seconds, once the skip ad button is clicked you get payed.
You can find an example by clicking this link http://adf.ly/4PlKi