The iTunes software is performing a check when a user creates a new account to verify that the address of the user and his payment address are related. A credit card for instance would have to be from the United States as well if the user would select the United States as his country of residence. It is therefor not possible to create a US iTunes account the "normal" way unless US address and credit card are at hand. One way to get past this verification is to buy gift certificates and use them to create the account.
Some users probably prefer not to pay any money for the account because they just want access to the free contents and never make a payment in the store. The good news is that it is possible to use used coupons as well to create a free US iTunes account. Gift certificates could later still be used to add money to the account in case a purchase has to be made.
The benefits of having an US account are access to free songs which are updated regularly, to better promotions and music, movies or tv shows that are not available in other iTunes store yet.
The first thing you do is to download the iTunes software and install it. Once that is done start it and locate the Redeem link in the top right Quick Links menu.
This will load a page with a form that accepts coupons and gift certificates. All you need to is to paste a coupon code into the form and click on Redeem to send it to iTunes. Coupons can be found here or here.
The iTunes software will throw an error message if the gift certificate or coupon is no longer valid. That however is not a problem at all. Return to the homepage by clicking on the home icon in the upper left corner of the iTunes store.
Once the homepage has loaded it is time to create the account. You can do that by clicking on the Sign In button on the upper right corner of the iTunes store. It offers you login possibilities and a button to create a new account. Click on that button.
Click continue on the welcome page and accept the terms and conditions of the iTunes store in the second. This finally leads to the account creation page.
Enter your details on that page and continue to the next and final step of the account creation.
If everything went well you should now see the page where you can select a payment method and enter the address of the account. The payment method has to offer None as one option for this to work. If that is the case choose none. Now you need to enter an US address in the last step to create the account.
The zip code, state and city have to match. Everything else does not. Just select the location of a friend or relative to be on the safe side but it is practically possible to enter any information you like.
The account will be created in the last step and the contents of the US iTunes store are now available.