Um. How much does it cost the bank? Zero. Or very close to it. Unlike banks outside of North America, US banks earn well over 50% of their revenue from fees and charges.<p>The typical banking model of net interest margin (the amount earned by the difference in savings &#38; loan rates) dominates revenue elsewhere. The American market, however, is so lacking in competition that they can get away with charging hidden fees and charges.<p>Sure, it helps if you check your balance. But do you read your full terms and conditions each time your bank changes them. I spent most of my summer reading the T&#38;C's of every major bank account in America. You'd be very surprised by what they contain.<p>Here's a personal favourite of mine: most banks would retain the right to re-order your transactions in any 24 hour period before settlement so that withdrawals for large amount came before any smaller amounts, and then deposits were posted in reverse order. What this means is that if you were to start out the day with $100, then have a $2,000 check clear and post to your account, you could go out and make a purchase in the afternoon for $500 and _still_ get hit by an overdraft fee. And if in the morning you made a few $5 purchases, they would _also_ incur the $35 (median) overdraft fee, despite the fact that if the balance was updated in chronological order you would incur no such fee.<p>I say 'would' as this practice is being phased out. That said, overdraft fees, while expected to earn $40bn for banks in '09, are only about 7% of overall revenue. There are plenty of other tricks that banks have up their sleeve.<p>Falling back on the argument that banks are allowed to do whatever you agree to in your contract is intellectually and morally dishonest. No one reads their T&#38;C's. Banks know this and use many invisible and often unavoidable fees to earn excessive revenue from unsuspecting consumers.<p>And even if you were to level the playing field in terms of fees and charges, banks are sluggish and don't grok what it means to have a good online experience. We are working on fixing this.<p>If you want to speak with us in more detail, track us down and we'd be happy to chat.