EDIT: [About the editors, it takes an hour and sometimes more for a link to be killed, at least when I flag a link and I see it for hours - happened today. So maybe automation will help in any editors shortage]
For example, someone few days ago submitted your article "Why TV Lost", although it was already submitted, and we already discussed it! But he was able to do it, obviously because the submission detection script does not think that "www.domain.com" is the same as "domain.com", and treats them as different links.
Also if a link is submitted previously and it was dead because it's spam, then if a user tries to resubmits it again it should be killed automatically. Like Google homepage, myspace and all of these bla bla bla.
There are zillion techniques for preventing spam, and you know it better than me for sure. But there is a vision that you have about spam on this website, that I don't really understand yet.