I came across an article, "How To Keep Hostile Jerks From Taking Over Your Online Community" on Seth's blog. It is really relevant to anyone who runs a forum, blog, message board, mailing list, or anything where people can join and comment.
Definition troll (n) -- someone who comes onto an online community looking to pick fights -- has two victory conditions: Either everyone ends up talking about him, or no one talks at all.
Trolls can infect a small group, but they really shine in big forums. Discussion groups are like uranium: a little pile gives off a nice, warm glow, but if the pile gets bigger, it hits critical mass and starts a deadly meltdown. There are only three ways to prevent this: Make the pile smaller again, spread the rods apart, or twiddle them to keep the heat convecting through them.
Teresa is a troll-whisperer. For some reason, she can spot irredeemable trolls and separate them from the merely unsocialized. She can keep discussions calm and moving forward. She knows when deleting a troll's message will discourage him, and when it will only spark a game of whack-a-mole.
Teresa calls it "having an ear for text" and she is full of maddeningly unquantifiable tips for spotting the right rod to twiddle to keep the reactor firing happily without sparking a meltdown.