Buymobilephones.net currently have a few contracts that are free after redemption and they are paying £30 Quidco. Choice of not 1, but 2 awful phones! They are on orange so you also get 2 for 1 cinema tickets, free itunes films and the Panther plans also include the free swappables such as Sky sports on your phone. If you are good at organising cashback (5 emails in 18 months), then I think this is a steal. The 18 month deals are probably easier to manage but you can get slightly cheaper 24 month contracts,
Links in post 3, I'm a very slow poster!