Simply put [and stealing from Peter Singer]: how are we to live our lives? Everything else [that matters] follows from this question. Ethics is also about always asking the question of what is unanswered, undone, unaddressed, unregarded, unloved, and unfinished. It addresses all the places of incompleteness in a society--in its laws, its charters, its bills of rights, its institutions. Ethics will always be more important than "rights"--which are political--because rights are always predicated on categories that, by their very nature, exclude someone and something. Ethics attends to these exclusions. Ethics locates itself in all the places the law either overlooks or damages. There can never be, say, a *written* ethical code, because real ethics are, in some sense, unsayable, but never undoable.
Her commentary in its entirety makes good reading.
For a related -- but far lighter -- discussion of etiquette and its possible relation to something like ethics, check out the lively comments on this odd column about a Ball o’ Butter at Inside HigherEd.