I have just returned from Florida and I have a US mobile phone available. It is on the Net10 network, which means that all calls within the US are 10c per minute and International calls (e.g. to the UK) are 15c per minute.

It has $28 worth of credit and it's activated until 6 August (Note: in the US you buy both air time and activation time - $20 buys 200 minutes and 30 days).

If anyone is travelling to the USA before August and would like the phone, please PM me. I'm looking for something back against the $28 credit.