What's the deal with your nickname? How did you get it? If your nickname is self-explanatory, then tell everyone when you first started using the internet, and what was the first thing that made you say "wow, this isn't just a place for freaks after all?" Was it a website? Was it an email from a long-lost friend? Go on, spill it.
Half-hearted browsing of Sailor Moon fansites gleaned from Yahoo! and correspondence with friends of yore aside, my first real foray onto the intarwebz consisted of Neopets. Which probably gives you a good indication of my age.
My username there, for lack of a better idea, consisted of a cute fuzzy animal and an alliterative adjective. Very, very original. I liked the alliterative pattern, however, so when I migrated to Fanfiction.Net two years later, I went with "Phire Phoenix". Phoenix because the life cycle of this mythical bird is how I try to live my life, and Phire because Fire Phoenix looked stupid.
Eventually, the people I talked to via FF.Net and various other forums started shortening my name to Phire. It stuck enough that my real life friend and fellow-fanfic-fanatic (See, alliteration again) regularly called me that in real life for serveral years. I've been various incarnations of Phire ever since - one of my friends first met me through the LJ of a mutual friend, and for two whole years, despite having met me multiple times IRL, did not know my real name. I was, to say the least, amused when I found out.
My semi-permanent home is MetaFilter now, since I spend about 80% of my non-work Internet time here, to my chagrin. I tend to lurk because I prefer keeping quiet if I have nothing interesting to say, which has the interesting side effect of me feeling like I know most of the regulars here when I ... don't? Heh, yeah.
Side note: I also seem to be the only MeFi who genuinely likes lolcat. Hmm. I feel mature now.