Today I obtained a EIN and submitted W-8BEN forms to Amazon, CreateSpace and SmashWords. Obtaining an EIN was required in order to submit the W-8BEN, and the W-8BENs were required in order to receive royalties from these U.S. based publisher/retailers, as a 30% withholding tax is otherwise applied to royalties before they're sent to an author. As Canada has a tax treaty with the U.S., all these forms permit us to receive royalties at a 0% tax withholding.
All this applies, of course, when you're not a U.S. resident and don't pay U.S. taxes. This must apply to a lot of people, since so many authors are pursuing this route in order to become published, including a lot of international authors.
You can learn more about the process at the following blog, where a few kind people have graciously documented a simple process for getting this done: http://catherineryanhoward.com/2012/02/24/non-us-self-publisher-tax-issues-dont-need-to-be-taxing/.
So glad to have finally done this. Another check mark on my "to do" list!