There is a "pay per use plan"
$15/day.
That's more of a pay per day. When I said pay per use I mean pay per MB used
That would suck to pay $15 for a day and not use $15 worth of data. It would be cool though if you paid for $15 worth of data and had it expire in a week or two. Kinda like Virgin has theirs setup
http://web.virginmobileusa.com/broadbandPlans