To put credit on a US itunes account you can also now buy digital itune cards at bestbuy.com for internation delivery and the redemption code will be automatically emailed to you.

On a recent QFA380 flight I used a 100mb allowance checking mail and a few websites.

I travel to Montreal and for a flight this week the SYD - DFW flight arrives too late into DFW to make connections to Montreal so am travelling through LAX.  On the way back I will be in Charlotte and have booked onto the DFW - BNE flight which is a good connection.