So how can these companies give away free gifts?
It's called Affiliate Marketing. When you sign up to Real Incentives, and complete an offer (for example, LOVEFiLM), the advertisers pay Real Incentives a commision. When you have referred the required amount of friends, the money Real Incentives are paid adds up to the price of your Free Wii, plus a little more for Real Incentives' profit.
Here's a table so that you can see how Real Incentives make their money:
