One of the easiest ways of making money on the internet is to set yourself up as an affiliate. But it doesn't mean to say that you sign up with every single affiliate program and then spam everyone!
The best affiliate programs are the ones that give you good promotional material, not just banner ads, but brandable eBooks and reports for example where you imbed your affiliate link inside and ones that give you specific step-by-step instructions on how to promote.
Here's a very good tattoo affiliate program that I'm using that's making me about $50 a day;
http://www.tattoofever.net/affiliates
Regards, Marta