Actually, the U.S. Netflix will accept some Canadian credit cards. My account is linked to a Capital One Mastercard. For a zip code, I just used the 3 digits in my postal code, and appended a "01" to the end. If you're going to try this trick, make sure that the zip code you use is actually a valid one first.
Some people have had success using their AMEX cards as well. I already used mine for my Canadian account, so it didn't work for me.
I'll also note that some users are reporting that their Canadian Netflix accounts are flawlessly streaming US content with unblock-us enabled. I had some issues with my ATV2, even properly configured, when trying to use my Canadian Netflix account. So I just switched to a US account.
I've created quite a few US based accounts for various things, and I have to say that Netflix was probably the easiest one to set up. Very few hoops to jump through.