Ever play Red Planet or Battle Tech? Well if so you gotta have a call sign. So back in '93 when I started playing Red Planet I chose Cool Hand, from the book “Flight of the Intruder”. It stuck and I have used it since for e-mail, chat, and posts. Though some shmo’s got it on here so I had to use an underscore between names. 
Great topic CoolHand, I can’t wait for some of the explanations. My UserName, for those who don’t know already is the name of one of the “natural”, Pre-Socratic philosophers. ca. 460-360 B.C. He was the first to come up with the concept(along with Leucippus)that everything is made up of eternal, immutable atoms moving in space.
I chose the name because of my interest in both physics and philosophy. Democritus lived in a time when there wasn’t such a seperation between the two fields. This I see as a huge problem these days.
Also, the first name I wanted was taken(and desecrated)…Phaedrus. Damn him!
“Teaching without words and work without doing are understood by very few.”
-Tao Te Ching
This has come up before…
Still, I will respoond because the spirit is weak.
I got my name because I hte all Christians and love evil.
Okay, not really…
Actually, I took this name for shock value, combined with a healthy need to play Devil’s Advocate in a lot of situations.
Besides, the Devil always has the coolest tunes…
Yer pal,
Satan
I love this topic! To see the previous thread go here: http://www.straightdope.com/ubb/Forum4/HTML/000457.html which has a link to the first incarnation. Definitely recommended reading.
Ah, mine in an earlier thread yet.
And no, I am not a gay type of bear.
I’ve replied before, but anything to artificially inflate my post count.
Chris Mullin is my favorite basketball player. I am a huge basketball fan. Mullinator sounds cooler than anything else I could come up with.
Well, shut my mouth. It’s also illegal to put squirrels down your pants for the purposes of gambling.
Short for Don Juan the Lover of Women and Envy of Men. Don Juan is always taken so I shorten it up to Donj. I did not adopt this name on my own. I picked it up from my friends because of my ‘not so smooth’ techniques of meeting women. =)
–Donj
A little boy who was banished to the Pointless Forest because he didn’t have a pointed head like the rest of the villagers.
c.f. The Point - Harry Nilsson
A point in every direction is like no point at all
Lack of originality… I was only intending on visiting at the time, not staying.
I am me… accept it or not.
M.L.A.W. are my initials. Used to be MLAR until I married. I jokenly say to my SO that I married him for the “W”.
BTW - my first name is Lynn.
I thought Gail would be an easy screen name to remember…since it’s my first name.
–Gail
“Predictable, really I suppose. It was an act of purest optimism to have posed the question in the first place.” --John Cleese
Well, it’s actually a CIA undercover name… if I told ya what my real name is, I’d have to kill you.
Yes, I am a brat…and it’s hard work!!
Same here.
My name is the FCC assigned radio call sign for my employer.
Jeremy…
Anyone who says they don’t like children obviously isn’t cooking them properly.
Easy enough to explain, but a dull story. College nickname which has somehow stuck through the years
Hello. I’m SanibelMan.
I’m a man… from Sanibel, a Sanibel Man.
SanibelMan.
Not San Ibelman or Sani Belman, just SanibelMan.
Clear? 
SanibelMan - My Homepage
I could be doing something, but… why?
First initial & Middle name (no, I’m not related). Original screen name from the old PC Link days before it degenerated into AOL. Lost it when they changed over and somebody else swiped it so now I use “ver#”. I’m up to “JBENZver5” with AIM.
I think Polycarp and I have the oldest surviving PC Link screen names.
JB
Lex Non Favet Delicatorum Votis
It’s evil. Sneaky evil. Not blatant, very subtle. And that’s all I’m gonna say. 
Best!
Byz
I have no idea.
its part of my email address (the B_Line part has been in ever incarnation of every email address I have ever had) My first name begins with B and my family calls me just B most of the time, so for an email B_Line… as in straight line right to me OR the electronic line to B. The 12 part? well… had to add it to hotmail cause someone already had B_Line… I think they just suggested it.
Oooo…long story. Let’s just say, one evening, Canadian Sue and I decided to errr…ummmm…liven up a chat room…I have to say it was alot of laughs and I learned more than I ever did reading the book “everything you ever wanted to know about sex but were afraid to ask”! Yeah!..that’s the story and I am sticking too it!
“Only when he no longer knows what he is doing, does the painter do good
things.” --Edgar Degas