I've been known variously as:
shadowritten - name of my first freelance copywriting venture
Mark Antony Owen - I'm sure I used this for a while: my real, full name
~ M A O ~ - no, not the Chinese ...

~ M a r k ~ - had this one for quite a while, because the one I have now wasn't free
I've also popped back under at least two other names during a long period (about three months) when I was supposedly 'on a break' from this place. But I never revealed who I was (except to a couple of folks here), and I deleted those accounts fairly soon after creating them.
Yeah, I know. I can be odd at times.
