At first I used David (now there is pure genius for you!), then I went away for awhile and had troubles logging on, so I created djb, which are my initials (again, more creative brilliance).
I do have two nicks on other groups. "Kottbullar", which means "meatball" (as in Swedish meatball). And the other is "vrangskalle", which translates to "perverse head" or "obstinate head". "Vrang" being the insult and "skalle" being the skull or head.
I have yet to use "surskalle" as a nick, which means "sourhead"!