"Axtech" was actually the first original username I thought of (other than, of course "Robert" or "Marshall1" or something stupid like that). I was sitting at my comp, looking around the room for ideas, when, lo and behold! The gleam of light on my guitar's tuning knobs caught my eye. This was when I had my first electric guitar (I've changed it since). It was a black-with-white-pick-guard cheapy I'd gotten soon after starting to play (I started on an acoustic, but switched to electric after a short while). The brand name on the guitar was "Axtech". So, I used that as my name, and it's just stuck with me. I've since searched for the company online, but either they're a company based in an Asian country, whose website I can't read (I found such a site, but I think it might be something else), or they've gone bankrupt for selling crappy products.
So, now I use the name as an homage to my first (electric) guitar, and because it sounds cool.