I like to consider myself an enlightened guy about most things, but I must confess here to one remaining form of prejudice: I tend to judge people, however unreasonably, by their first names. For instance, when I hear the name 'Darren' I can't help thinking 'white trash', while I think extreme Irish names like 'Tadhg' and 'Fiachra' might as well be written nouveau riche and Cumann Fianna Fáil. And while I don't find it inconceivable that I could like someone called Turlough, the name would certainly be a major obstacle.
I extend this name prejudice towards anonymous online handles, in the sense that I hate them all unreservedly. It's partly just their self-appointed nature. Where I come from (and indeed in most cultures), a nickname is something you earn, something given to you by your peers as a mark of respect. So when some lamer appears on Usenet and expects me to call him El Presidente, my immediate impulse is to say "Okay, and what's the name your parents gave you?" In fact, I veer towards thinking that names in general are things given to you by other people. This is one reason I didn't choose an optional extra name at my Catholic coming-of-age ritual. To give myself a name would seem... well, presumptious. What has it got to do with me?
Of course, 'something given to you by other people' could easily be rephrased as 'something imposed on you by other people'; and it could be argued that people who give themselves names are making a statement of independence or defining their true selves or performing some other Oprah-style act of personal liberation. And indeed, I can sympathise in some cases. If my parents had called me 'Depressed Cupboard Cheesecake' (as a British couple did to their child in the 80s), or worse, if they had called me 'Oisín' or 'Senan', I'd certainly want a trade-in as soon as possible. Changing your birth name to one of your own choosing is certainly a powerful symbolic act, a decisive way of breaking with the past.
Such wholesale name changes, however, are quite different from online handles, which are often merely vanity. Certain users feel the need to bestow upon themselves such modest titles as 'UnixGod' or 'The Pro' once online, and these people deserve all the school bullying they get. And then there are certain fan subcultures and online communities which more or less enforce the use of handles -- communities where you can call yourself __katygothchyk, but where plain old Catherine won't do. But I've complained about them elsewhere.
Maybe people think that an online handle frees them from the restrictions of their day-to-day identity, or gives them some room to express themselves, or something... but if you think this, the problem is not with your name, it's with you. All such arguments ultimately boil down to cowardice: the fear that your own vulnerable opinions will be exposed and ripped to shreds. If you give yourself a false name, you can pretend that the pseudonymous lamer who has just made a fool of himself on Usenet is not you -- but that's just a delusion. You don't stop being you, ever, and you're exactly as lame (or as interesting) as your pseudonymous alter ego.
A rule of thumb for online communication: unless you're willing to put your identity behind it, you probably don't have anything worth saying. This holds true for about 99% of the conversation I've observed on the Net, and holds especially true for rec.*.int-fiction, where there is a one-to-one correspondence between anonymous handles and people who have never once said anything interesting.