Odin, Blood, Legend, Blood Legend, Merc, Godling, Rahn, Rahnzan, Renzo, The Phil.
Odin was brief. No one calls me Blood, Merc, or Renzo anymore, Blood Legend is only on a few forums, Rahnzan is typically my handle for certain messangers and my gamertag wherever applicable, Rahn is what it typically gets shortened to when people try to talk to me. That name by the way is pronounced sort of like an inbetween of "Ran" and "Ron" or "r-ah-n." The Phil is the only real-world nickname I have. Godling is a name one of my dear friends still calls me by because I once used it in an MMO and I guess it sounds a bit too cute to let go.
I typically answer to Rahnzan, Rahn, Godling, or Phil. I use Rahnzan because the internet (and xbox live) is usually full of idiots whom I'd rather not associate with. This nickname distances me from that. I'm not ashamed to tell people I trust or announce in a responsible section of cyberspace my real name, but I wont respond proper if I'm playing a game. It's like 'Phil' is out-of-character and Rahnzan is in-character.
If I'm playing Left4Dead, you could go "Hey Phil, hows yer mum?" and I'll typically respond. But unless you ask for Rahnzan when you need help with a Smoker, it's probably going to pass over me.