Just rang for my PAC code to move to GiffGaff but when I told them this they asked why (usual). Told them I wanted unltd internet and to keep at £10 per month on a rolling 30day deal. They gave me the following for £10.43 and told me it's available to any existing 30 day customer (my friend rang after me and got the same deal so can confirm it's not a one off retention deal).
600 Any Net Mins
UNLTD Texts (fair use of 3000 p/m)
UNLTD Web (Fair Use of 1GB p/m)
No comitment period, 30 day rolling contract.
I won't go over 1GB on my phone, and I don't think they exactly police the fair usage policy anyway. 600 any net mins plus the texts for a tenner can't be bad IMO.