We need a slashdot-style moderation system where people retain "karma" of some sort based on their posts. That way we could moderate people as "troll", "idiot", "spammer", "complete newbie" and have them automatically filtered. (Of course, we'd have to create a "Newbie forum" where newbies weren't filtered... it's not their fault so we shouldn't block them completely.)
And these moderation tags should appear right under their names, next to (or in place of?) the titles, so that people can immediately see "oh, he's just a troll, let's ignore his crazy post", or "hmm, that new web hosting company is run by a complete newbie, let's move on...".