I really quite despise sites that have rigid rules around usernames. General courtesy rules (e.g. such as no profanity in a username) are fine, but any site that tries to force me to use my "real name" I find immediately frustrating.
The most recent tussle with this problem was with Facebook. Their registration system really tries to box you into using your real name. I entered "r3v" and it told me, "You must provide your full name."
So, then I changed my entry to "r3v zero". (r3vZERO, r3v.zero, etc are names I tend to use when a system won't allow me to use a three character name. (e.g. XBox Live) It's like adding a 0, without making it look like "revo". Heh. Other times, I use "xt0ph3r". (e.g. Digg, Myspace) Another pet peeve.)
"The name contains invalid characters." It doesn't like the 3. I can't have a number in my name, it seems. So, I de-1337ed and tried "rev". No go, of course because last name needed. So, now I'm "Rev Zero" on facebook. (They enforce capitalization.)
End result? They still don't have my given name and I'm stuck with a stupid username. Neither of us are happy. What good was that?
Some might argue that I should have just given in and used my given name, but why? I don't use my given name for nearly anything online, including sites that grant a fairly large, if not boring, view into my personal (aka real) life. The vast majority of my friends either know me only as r3v, know me primarily as r3v or, at least, know that's what I always try to use online.
I've actually put some effort into it. (r3v.com is a three letter dotcom, ya know. Wasn't cheap to kick the squatter off.)
Therefore, "r3v" is almost always the best way to find me, or even find out more about me. Forcing me to use my "real" name (or some made-up bullshit) is actually COUNTER productive.
They should have leveraged one of the things that MySpace actually GOT RIGHT. Myspace allows you to enter your given name, but keeps it hidden and allows it to be searched on. As a general rule. it's bad when MySpace does something better than you. K?
PS: (I haven't committed to the "Rev Zero" name yet, I'm still looking for a better way to game their system. I have, however, gone ahead and added it to my ClaimID.)