The oddly named Reestit Mutton site catalogs the cash-back and discount deals offered by UK mobile phone companies, figuring out all the angles — follow their directions and assiduously apply for all the rebates and suchlike and you can get your phone and service for free (apparently in some cases, you can double-up on rebates and actually get paid to acquire a mobile and a year’s service).
(Thanks, Niall!)