People suggesting a reddit/metafilter/slashdot style meta-moderating system are making the dangerous assumption that 'legitimate users' outnumber the trolls
Trolls will be quickly destroyed by lowering their reputation.
And also only users having 50+ posts [the posts also cannot be rated too negatively] and registered for at least 3 months will get moderation rights. This way it is extremely hard for trolls to overcome legitimate users, even if they outnumber them many times.
Additionally, "real" forum moderators may lower the reputation of persons behaving extremely badly even further.
