I came into fandom via Smallville too, waaaay back in 2001, and I couldn't seem to come up with a suitable username in relation to Smallville itself, though to be fair it had been on the air for less than one whole season at that point! So, I went back to the Superman canon that I knew before - Lois & Clark: The New Adventures of Superman. My favourite episode was always Ultrawoman, in which Lois gets to be a superhero for a while. Chose the name on a whim and it stuck. 20 years later, everybody I know online calls me Ultra and it doesn't even seem weird to me that that's my 'name' anymore! lol