Get a Vodafone SIM only contract from PhoneBoxDirect and you'll receive a FREE Xbox 360 Core edition and a FREE iPod shuffle, worth about £260 (£50 for iPod shuffle and £210 for Xbox at Amazon). Purchase via QuidCo.com for £30 in cashback too!!
The contract works out at £360 for the entire year, after which you may cancel. If you take away the QuidCo and the value of the free goods it works out at about £70 for the contract... a safe alternative to cashback!!
The vodafone contract gives you 200 free x-net minutes every month.