As a general rule, I'm not very creative with names. "kineko3", a username I've been applying to various accounts since high school, came from my cat's name and my favorite number.
Yes, my cat's name was "cat". Sure, it was in Japanese, because I went through a phase when everything Japanese was *really, really cool*, but still. Cat. Anyway, after going through all that trouble to pick a name for the cat, it made sense for me to just use it everywhere else. Slap a 3 on the end because--surprise!--someone else decided "kineko" was a good username before I did.
"syndaria" has its own unique story. When I wrote science fiction, I created a world 1000 or so light years away, with higher gravity and a hotter climate than Earth, where a group of humans ended up stranded as a result of FTL travel gone wrong. I don't write fiction anymore--the enjoyment I get out of it is not proportional to the amount of work I put into it--but the story of Syndaria still writes and rewrites itself in my head.