This is quite a good website http://www.quidco.com/ You get cashback on loads of sites.I use it whenever I buy a game or DVD online.I even got £120 from vodafone when I took a sim only contract.
how does this website work?
they get a referrer fee for purchses made after going from their website, some of that fee is given to you and a percentage is kept by the site
how does this website work?