This system can be built by the community rather than the banks. It is absurd when banks pull in billions of dollars for contributing basically nothing to society. If this is a system that has to be pushed by the banks you can guarantee the ones who make the most money will be the banks. I'm digressing again. I can picture this being the next big hype segment by the way.
Users deposit an amount in a single, centralized micropayment house.
The micropayment clearing house replies with the confirmation that the monies were transferred to their account. The user reads pages, watches movies, plays games, etc. If billed at intervals every now and then the site connects again with the same info and requests a new transfer. When the limit is hit it notifies the user who has to do the process over again. There are several keys that differentiate this from a lot of existing systems.