Taken from Somethingawful.com -
The Internet Gadfly is easily mistaken for a troll, but is actually far more
pathetic and common than the troll. Whereas a troll is an artificial construct, the Internet Gadfly is desperate to invest himself emotionally in his attempts at disruption. The Internet belongs to him and how DARE you do something of which he does not approve. The Internet Gadfly will often initially seem benign, but he will soon attach himself to the
power structure somewhere - on a forum, on
IRC or even on Usenet - and then things will
go horribly wrong. Internet Gadfly will begin griping constantly and
pushing boundaries. He will eventually attempt to foment rebellion and, failing this, retreat to a sort of sub-community that exists solely to harass the community that exiled him. Fortunately, Internet Gadfly will find many
outcast comrades to take up the cause with him.