Amazon’s interface for signing in and out is pretty confusing.
The only way to sign in is to click “personalized recommendations”. The “sign in” text isn’t clickable.
The only way to sign out is to click the name of the person who’s signed in:
Clicking someone’s name generally takes an action related to that person (e.g., opening an email to him). At the very least, Amazon should have made the entire sentence (“Not Tom Lehman?”) a link.