The online identity, or what I like to call the Internet Identity, is one which is very similar to ones own social identity.
You say your name is Robert Paulson? Ok. Then I will call you Robert Paulson. You are known as Robert Paulson. When you introduce this person to other people you say, "his name is Robert Paulson".
Why so static? Why is he known as Robert Paulson in one place, and not John Barker in another? Why is he not known as jfchrist666?
One word: Convention.
Now my question is, why do we have different names for different places on the Internet? There happen to be some interesting good reasons not to do it. If someone malicious finds your Internet Identity, the risk of your information being stolen increases. The probability that you will be stalked, specifically known as cyber stalking, also increases. Another simple, but crucial problem is the availability of the name that you choose.
You can certainly protect your information better if you have a different password for each account or if you regularly (though irregularly sometimes works better) change your password.
Cyber stalking on the other hand poses another problem, where it is slightly harder to track things. Thanks to the expansiveness of the Internet, there is a website dedicated to just this topic.
If you have ever used AOL's AIM client, you might know how hard it is to find a unique name. This poses a huge problem if two different people have the same name in the global network. The current solution to this problem is to append some sequence of numbers or letters before or after your name. A good name is, of course, one which is readable, and without random letters or numbers. The ideal name, as well as being good, is one which when searched upon gives results which relate to a person first, followed by lingual definitions and encyclopedia entries, if such apply. Finding such a name requires creativity, luck, and patience.
So where are the pros? You're right, I haven't gotten there yet.
The coolness factor: Don't you think it would be cool to do a Google search on yourself? Your identity, everything you've done on every website (without a robots.txt blocking Google) you've ever (probably) joined is stored within Google.
Somehow, I can sense a lot of you are cringing.
Identity: There also comes a sense of identity; although this sounds obvious, it is new because this identity extends throughout the entire Internet. This identity isn't localized to one website or online community. If you are known by a single name on the Internet, the absence of your name in an online community will imply that you are not part of that community.
Global and Social Efficiency: In an increasingly global society, the emphasis of the individual is becoming greater and greater. It will become more and more inconvenient for one to go by 10 different names on 10 different internet communities. Not only will you, the representative of those names, become annoyed as you join more communities, but also your friends will become more and more annoyed trying to remember all of your names along with all of theirs. It's a complete inefficiency.
In five, ten, fifteen years, it may become the case that the reality that one lives in life is similar to, or is ones life on the Internet.
Also by this time, we may completely solve the problem of duplicate names on the internet. In "real life", we have two types of identity, ones name, and ones physical features. In the future of the Internet, we may have another form of identity which is constant like our physical features, which extends beyond the name, the picture associated with our profile, and the way we use language in our posts and nodes.
I have dedicated myself to an online identity, or Internet Identity, and I feel good to be defined in a physical sense and in a virtual sense.