seems finland is #1 with 75% of the population classified as internet users. that means everyone for me btw (because babies can't possibly be internet users do they?)
i think the answer lies on how you design the charging system. if users have to through a cart/transaction system, micropayments would never work. it should be simpler (say, with one click) with as less friction as possible.
micropayments are good for microservices. say you want to use basecamp for 1 week but dont want to pay the monthly service. itunes music store is another "microstore".