I chose my username and profile picture from something I liked. Boba Fett has always been one of my all-time favorite fictional characters. I had his action figure from the Droids cartoon when I was little (earliest Boba Fett figure I remember owning, I have many more since then):
had the Marvel comics adaptation of Empire Strikes Back, poster on my wall, stood on a line that stretched around to the back of the theater to see "Return of the Jedi" (only to see him ignominiously launched into the Sarlaac Pit!), I had the "Battle at the Sarlacc Pit" board game:
Basically, I was a Boba Fett fanatic before "Respect the Fett" permeated pop culture. I can remember searching for Boba Fett websites on Yahoo in 1995 when only 3 results would come up. A google search today brings up 14,300,000 results.
Anyway, Boba Fett wore Mandalorian battle armor from Mandalore, to which I added the last two digits of my birth year to arrive at my username: Mandalore76.