My go-to commentary on this general topic is the classic penny-arcade comic "John Gabriel's Greater Internet Fuckwad Theory"
(Normal Person) + (Anonymity) + (Audience) = (Total Fuckwad)
(Normal Person) + (Anonymity) + (Audience) = (Total Fuckwad)
See: Banality of Evil http://en.wikipedia.org/wiki/Banality_of_evil
and, http://www.radioopensource.org/hannah-arendt-and-the-banalit...