You just described the payment model Apple negotiated for the iPad. No contract, no subsidies, just a flat payment: $x for $y GB in 30 days. If you don't use

You just described the payment model Apple negotiated for the iPad. No contract, no subsidies, just a flat payment: $x for $y GB in 30 days. If you don't use it in 30 days, it's gone, but if you use it in less than 30 days, you can just buy another block of bandwidth (and restart the 30-day counter). I think it's great, especially when travelling to different countries (which seem to all offer this option - only for iPad).