Well, I was told that Caitrin was the Welsh translation of my real name, Kathryn, and I liked the sound of it. Of course, Jon Freeman has informed me that I'm probably spelling it wrong. : ) He pronounces it a lot prettier than I ever did, too.
In the 3-d world, I'm usually Kat or Kate. I've also acquired Captain Sarcastic and Katie Kaboom, too, but those are generally used to make a point at me. : )