FORTUNE — The value of those 800 million iTunes accounts — most of them attached to credit cards — is starting to have an impact on Apple’s (AAPL) bottom line.
Part of Apple’s 24% increase last year (to $18.3 billion) is due to an accounting change: For the first time, Apple threw online hardware sales into the mix alongside iTunes and App Store sales.
Amazon’s retail offerings, of course, are considerably broader than Apple’s. But as Asymco‘s Horace Dediu pointed out in a chart posted on Twitter last week, Apple has the edge in terms of online accounts. Those could come in handy if Apple, as rumored, is working on a new, iOS-based mobile payment service.