How can I separate my personal Amazon account from my AWS account?

Solution 1:

I've received confirmation from Amazon that this is no longer possible and that the page linked in my question is out-dated. I was advised to use Identity and Access Management (IAM) should I need to provide multiple users access to one AWS account.

Solution 2:

Some (most? all?) email services support using + to append arbitrary suffixes to email addresses; for example, email to me+throwaway@example.com will be received by me@example.com.

I use Gmail, and just signed up for a new AWS account using this mechanism; Amazon distinguishes my.amazon.account@gmail.com and my.amazon.account+aws@gmail.com, so I was successfully able to separate it from my regular Amazon account. I then set up a Gmail filter to tag/categorize incoming mail based on the +aws bit.