All the freebie sites are linked with other big sites, like LoveFilm, Gala, AOL, party Poker etc...

These companies want as much business as possible, so they pay sites to advertise them, this is where you come in...

When you sign up, the company will pay the freebie site because someone, you, signed up from there site, so if you refer 10 friends, they get paid 11 times, so they can afford to buy you an iPod, Laptop or Satnav, and they still make money.