"Paul" wrote:
[snip]
Perhaps it would be possible to have a system where TfL logs all the
journeys that you make in a month, and then works out how much to
charge you after taking into account daily caps and unresolved
journeys. This would be similar to the Congestion Charge Auto Pay
facility which is being introduced next year. People would have to
register a credit or debit card though, and presumably they could
check their account online.

AIUI such a thing is in development (albeit still in the early stages) - but
it would work directly with a debit or credit card's RFID functionality
rather than by using a separate Oyster card.