There was a good piece on this subject
in the Observer a couple of weeks ago. crabcakes' point about abuse is quite right. I'm friends with someone who blogs about gender issues using her real name: she's had death threats, regularly receives very explicit threats of sexual violence, and is exposed on a daily basis to the kind of name-calling and character assassination that would get a pupil excluded from school. Some of the abuse is orchestrated; much of it is ad hoc. What discourages her most is that so much of her time is taken up by people who have no interest in what she has written. All they want to do is drown her out, bully her into silence. And while she is tremendously fastidious in setting down her opinions, thinking them through, backing them up with evidence and anecdote, the haters just send her emails containing a few lines of gratuitous abuse and, occasionally, her home address. Much though she would like to, she can't ignore them.
On forums like Mailwatch where a small number of people post regularly, it's not really a question of anonymity so much as pseudonymity. If anyone has read all 700+ of my posts, they will have absorbed enough information to be able to 'identify' me. Knowing my name will not add anything valuable. Using a pseudonym allows me to set the boundaries of what other pseudonymous people can find out about me from the internet. There's also something liberating about it: I've always felt somewhat trapped by my 'real' names (which I have changed more than once — does that make them pseudonyms?) as they reflect an inheritance I don't necessarily identify with, but with which I become identified. They're also a public face I have to keep up: 'ezinra' can make dirty jokes and express controversial opinions, and allow them to remain in the public domain, in a way that 'I' could not.
Rudeness on the internet is a boom subject in the social sciences at the moment. Who are these angry people? What motivates them to be aggressive and abusive online? Are they aware of how they behave? What do they get out of it? From a gender angle it's quite depressing: the utopia of post-gendered 'cyborgs' communicating free of embodied social stereotypes has given way to a situation where: