Affiliate marketing, in which you promote a product or service and earn commission on every new customer you refer, is one of the easiest ways to start earning money online. Of course that’s not to say that it is easy to make a lot of money, but it does have the advantage that anybody can do it. There are actually hundreds of Bitcoin referral programs on the internet already. These are affiliate programs which either pay out in BTC, appeal primarily to users of digital currency, or (usually) both.