mine actually has a back story
it all started back in the day where games where played in arcades being wanting something that would stand out i chose the gamertag "rage" or "rge" depending on the game (i was young).
when i started play games online with Dawn of War (an rts for the pc) i needed a longer name. and at the time i used the Eldar allot with their Avatar.
did you see how it all came together? so now i use it for alosrts including forums and my PSN
if you want a dictionary deffinition here it is
avatar- temporary manifestation or aspect of a continuing entity
rage- Violent, explosive anger.