That's not as far fetched as you might think. The idea of paying for internet access with a "$cost/megabyte-transferred" is the fair and obvious way to setup things. We've been spoiled in the US with phones that have "unlimited dialing", and "unlimited internet accounts". But as more and more people get high speed access, the idea of putting an "information meter" at the entrance to everyone's house/business is going to come. These are "the good-old-days" which we will remember when the "meters" finally come. They will have no choice when the "glorious day" comes when we all have fiber-optic cables for connections. The "information-meter" will have to log 2 costs, the "number of megabytes transferred" and the "speed of transfer". I suppose there will be a way to convert that into one variable, but the idea will be lower rates for slower transfers, and non-realtime transfers.

Getting back to spammers, maybe the "meters" will be able to do "reverse-billing", where the spammers will have to pay into your account, in order for you to get whatever they want to send. I would accept spam at $0.10 a piece. That's what I charge for hitting the "delete key". :-)