Just a heads up, i got a phone before I left the UK from Fonepool (www.fonepool.com). You can get a phone & SIM or just the SIM and they post it real quick. Fonepool themselves were excellent but in my personal opinion T Mobile (the network fonepool provide) suck. I don't have any experience of other networks in the US, mind, but I thought they were outrageously expensive, customer service were awful, sound quality was too, and I only found one place in the entire of Florida where I could buy top-up cards (you can top-up over the phone too, but as they don't accept UK credit cards and my Vista bank account was usually empty...). Luckily it happened to be the Walgreens opposite Vista! I think you can top up in garages now too though. I've heard Virgin Mobile in the US are pretty bloody cheap esp for text messaging, but that's only what I heard . Don't forget that you'll be wanting to stay in touch with your new American and international friends too so I would definitely recommend getting a US cell number. I saw my roommate's UK phone bill at the end of each month, it wasn't pretty.