giffgaff is a sim only mobile phone company that runs on the O2 network in the UK. I heard about it by reading a blog post by Laura Cowen. After that I seemed to see adverts for it all over the web. Well I have not switched from my main contract yet, but I have just activated my sim with a £10 goody bag. If it works as advertised, I should be able to half my monthly bill.
Anyhow, anybody else wanting to switch to a Pay as you Go SIM only company, then by al means, click here.