Mine is short for "Radjamaki" which is a name suggested to me to make Cloud sound bad-ass in my first ever play through of my first ever Final Fantasy. Since then it stuck and I oft shorten it to Radje to make it easier to say and easier for others to spell.

I discovered a note I left for myself ages ago in the cover of a book that I had forgotten to read and it said "From James (Radje) age 13..." So it's been my online Alias since that age at least, though I think it was 12.