What is it?
It is known as referral marketing and the aim is to get the advertisers more customers. This is achieved by you and your referrals signing up to one offer each. Referral Marketing is a proven method of advertising and is a structured and systematic process that maximises word of mouth potential.
Why would they give me a free iPhone 3GS?
The freebie networks are commission based and they get paid by the advertiser for every offer completed through their site. The money they gain from the commission is what pays for your free iphone 3GS. Obviously they take a small profit out of each commission payment, but still set aside most of the commission payment towards your free iphone 3gs.
For example
You register on the freebie site and sign up to the Lovefilm two week free trial. You rent a DVD, watch it and then send it back.
Lovefilm would then pay the freebie site, this is their commission for referring you to Lovefilm. The freebie site will take a percentage of this commission as profit, and put the rest towards your free iphone 3gs. So basically the freebie sites are doing the same as what we are trying to do... referring people to do offers so we get commission!