This has been available for years in the US - a home equity line of credit that's linked to a debit card. It's a brilliant idea and can easily be used to beat a normal mortgage. One way of looking at this is that everything you spend becomes part of your mortgage (sounds scary, doesn't it?); another way of looking at it is that your mortgage is often your biggest financial instrument (even though it's on the negative side of the house), so why not work as hard as you can to beat it?
Consider this scenario: instead of putting your paycheck into a non-interest-bearing checking account and paying it out in dribbles over the month (and watching out for minimum balances, fees, etc.), direct-deposit your check into your home equity line ... lower your interest payment right away (these are normally calculated daily), and pay your bills with this credit card; most of those accounts are also accessible via a check book. And the 'banking' features are usually 'free' ... if you don't spend your entire check by the end of the month, your "savings" is automatically earning you whatever interest rate you would have been paying, on a daily basis. Try that with short-term mutual funds! And: if you have a bad month, some unforseen expense and you spend more than you made, you're automatically "covered" -- no overdraft problems, no scrambling to 'get credit' at the worst time (when you need it), etc. You're covered. And you should be! You're good for it! You own a house!
Voila: you're beating the bank by a lot.
It also COMPLETELY UNDOES the cancellation of "interest for personal debt" being tax advantaged: businesses write off 100% of interest paid, why not you? This is a good example of my point recently that we shouldn't take 'personhood' away from corporations, rather we should figure out how to become more corporation-like ourselves :-)
If you have a mortgage and you have ANY OTHER DEBT then you aren't worki ng hard enough; the consolidation of all your debt in your house is a really good idea in most cases: it's the only debt that individuals can incur that the economy/government gives any amount of respect to.
/jordan