There are a few trolls who need to be brought under control, but other than that, I see no need for extra moderation.
An ignore button would go a long way toward fixing that, IMO.
An up/down voting system with the result of enough downvotes in relation to the upvotes being a TROLL marking, similar to the SCAMMER one (maybe little troll icons instead of coins)?
I'm sure some of them would wear it proudly.
Ignore would be great. Voting system, not so much, as it could be easily abused. Just think about groups of trolls working in tandem, and how they could really screw things up with a public voting system.