"Dealing with Internet Trolls - the Cognitive Therapy Approach" is a "must read" article for anyone that deals with trolls in chat rooms, bulletin boards, and so on.
The strategy comes from Feeling Good: The New Mood Therapy, which is a self-help book that I highly recommend. In fact, I recommend this book in both TPOSANA and TM4SA.
Feeling Good suggests this strategy as a way for people dealing with periods of depression can deal with criticism. It works surprisingly well when dealing with trolls too.
The full article is here: