Display banners and get paid for clicked links.
So first thing is adf.ly, that's a website that gives you money for clicked links, whenever someone visit your website you get paid, whenever they click your link you get paid. So instead of sending a friend or sharing a link that look like this www.google.com you send this q.gs/google
Adfly = +- $2 daily
To double the earnings simply join CashPiggy, you know send people surveys and fill them out.
Those links are great but a better combo is links + banners and another popups so another great website is Clicksor. Clicksor gives you money for clicked links or banners, those ads are shown as image or even intext so theres a big chance people will click it.
Clicksor = +- $1 daily
Another option is to start trading stocks (seriously), I will invite you to website that earned me around $300, the website is called Etoro. And now I have invited you so you can start buying and selling stock market. Usually with Etoro you earn +- 3$ daily.
So that's 6$ with a little effort.