<p>I know how you feel. But this has been discussed on MSO, and so far this ability hasn't been added:</p>

<p><a href="http://meta.stackexchange.com/questions/3353/add-the-ability-to-ignore-users">http://meta.stackexchange.com/questions/3353/add-the-ability-to-ignore-users</a></p>

<p>There is a possible way to implement your own killfile mentioned in one of the answers to that question. </p>