I’m the only angelabaca that I know of.
My name doesn’t come from anything except for a Rene Descartes joke. Very intellectual. 
I tried to sign up to the Enjoy Incubus message boards and there was someone called that there. Aside from that, I am UNIQUE and ORIGINAL and the BEST IThinkNot EVER.
I felt like writing in caps so there you go. <snort> I’m a geek.
Apparently I share a moniker with a pit bull breeder. Go figure.
Over 30 hits for my username… sigh it’s not as uncommon a name as I thought!
I’ve just discovered that I’m a Lt. Gen. in charge of NASA’s Aeronautics and Space Transportation Technology Enterprise at NASA Headquarters, and I didn’t even know it!
http://academy.gsfc.nasa.gov/1998/html/lt._gen._sam_armstrong.html
Well, there’s this guy, if that counts.
I wonder if any of his parishioners have ever stumbled across any of the obscure lunacy I’ve posted to usenet and thought “What the…?!” 
Nope.
Apparently the hospital came first, but I ‘earned’ my name on a MUCK about 7 years ago, in reference to a Doonesbury cartoon.
Tripler
My name? It fits like OJ’s glove though. . .
I believe that my username is one of the most common ones in existance. You can’t swing a dead cat in cyberspace without hitting a Kat. 
I am the one and only fizzestothetop.
Google won’t even search my name without the spaces and there are only two links that come up, neither are usernames for anybody else. w00t.
I just tried Googling my username.
Four hits, all mispellings of “engineer.” I guess they’re hiring useless doofuses. Shoulda’ clicked the links, except I don’t want to move to Japan.
Evidently, I am unique and special, just like my mommy said.
I’m kind of surprised. I’ve never registered anywhere else, and surely somebody thought of this before I did.
There is a “Darwin’s Finch” over at the internet infidels message board who isn’t me. As far as I know, though, I’m the one who’s everywhere else.
“troy mcclure”- 7,330 hits, obviously
“troy mcclure sf”- one hit, the front page of the SDMB
“jjtm”- about 865 hits
“Duke” on Google…6,020,000 hits!!! Damn, I’m popular!
I’m happy to say that I am the only BraheSilver out there. When I search as two separate words, I get a great many hits, but nobody seems to be taking it as a name. Must be nasal envy.
My name has come a long way with me. It goes all the way back to second grade, actually. Computers were just becoming popular in school then. In fact, second grade was my first real exposure to computers. We had an old apple that we were using to learn how to type and spell.
We all had a screen name and a password with which we all had to sign in. Of course, the teacher had a list of all of those names and passwords so we wouldn’t get locked out of our work. The teacher (I guess it was all part of the “fun” of using the computers) had us all pick something original for our screen names. I picked the “B” out of the first letter of my first name and used my entire middle name. Then, since I thought it was required, I put the 13 at the end because I was the 13th student on the alphabetical class list that we all had which listed the old list that we had to delete in order to sing in with our new names. We were given the names because we needed to delete the old names to enter the new names.
The username and the password have stuck with me ever since. In fact, the only accounts for which I have ever registered where I have not used “bjohn13” have been my actual ISP accounts. When it comes to my personal email address, I prefer to use something that people can easily remember (my first initial and full last name…I wish everyone had an email address that simple).
There are other bjohn13’s out there. It frustrates me because I have no need for an account for which I can’t remember my username. There are also several other bjohns and plenty of bjohn1’s, bjohn2’s, bjohn3’s, etc. I guess it’s not all that imaginative, but I’m not about to give it up.
I was reading a thread and lo and behold I come across member GreatKingRat. I’ve beeen outranked, outflanked, and outgunned! (I’m guessing it’s a reference to the song by Queen)
(Mine is a reference to James Clavell)
The only thing that comes up on a google search for me is some site award given out by a Buffy fansite. So guess I’m the only one.
Well Duke, you have me beat. Ruby only got 5,350,000 hits!
I did learn something, though. I’m a programming language(Ruby) , a restaurant (Ruby Tuesdays), and a tourist trap (Ruby Falls).
Go figure!
I Googled roadkiller and it came up with some medical sites, and a “How not to be a roadkiller” site which is something along the lines of how to avoid killing animals with your car. Altogether it had 860 hits. I don’t know if anyone else is using roadkiller as a username, I am not currently a member of any other message boards.
My old name Blink178 only had one Google hit and it was for some Japanese site.
Well you would thing a name like Rabid Squirrel would be unique. First Google hit was an Internet Jazz collecter. There’s also a Linux distribution and an old college radio station dedicated to me 
I’m the only me.
A couple of “jk1245”'s turn up, but they seem to be catalog numbers of some sort.
Not too surprising since my screen name is the incredibly creative and witty combination of my initials and the address of the house I was living in at the time I registered.