There are a few options that I know of, but pretty much every one of them will cost more than you want to pay in fees, probably. You should be able to write a check/cheque to yourself. You might check with your US bank branch to see how much of a limit they'd have. You can also use a Canadian ATM card at a US ATM. The final option would be to use a Canadian credit card for all of your purchases in the US, and then pay the bill from the Canadian bank account. I don't recommend the last option because if you're not careful to pay off the bill every month, you're running up debt. Also, it's hard to pay some kinds of expenses by credit card, so you'd want a way to have cash available.
Another option would be to use a service like Paypal or Hyperwallet to send yourself the money. Again, you'd be paying fees, but these might be cheaper than what the bank would charge.
There may be other options, but these are the ones I'm aware of. Whatever you choose, look carefully at what the fees would be, and how long you'd have to wait to get the money. If you can plan ahead a bit, and take larger chunks of money at a time, that should help keep the fees down a bit. I believe there's also a point where you start having to report these transfers to the US government. The number $10,000 stick in my head, but they may have changed that recently.