My name here is... my name.
It makes it easier for people to find me and my musical/art stuff online if they know my name. The "D." makes it easier to differentiate me from the slew of other "Jorge Fuentes"'s out there.
You will not know what the D. stands for, though.
My online handle when I'm not using my real name is "TGMagus".
Magus is one of my favorite characters from the SNES era, along with people like Setzer from FF, so I picked Magus. The TG comes from another game, and it's one of the nicknames that one of the most badass characters has, so I took the nickname, and the magus name, and blended them into "TGMagus".
I use TGMagus on Skype, Steam, AIM, Youtube, etc.