Clicking the "Unanswered" link in the top-level navigation menu:
…shows questions that have no answers at all, whereas clicking "Questions", then selecting "unanswered" in the second-level navigation menu:
…shows questions which have no accepted answer.
Why should two links that are apparently intended to list unanswered questions show different results? I almost always forget which link does what.
Surely they should be labelled differently if their behaviour is different?