I used to be bio-brat until 2002. I hated it since the day I signed in, but I had only intended to answer a single Biology related question.
It was … um … wait, don’t tell me … I know this one …
I think it was admiral borg or something to that effect. That was way, way back in 2000 and 2001. I changed it after I returned from my 3.5 year hiatus last spring.
I was, briefly, known by my first initial and last name plus a couple of digits - used to be my network ID about 3 jobs ago.
Then I decided that was a tad lame and unimaginative so got myself hitched up with Frank Zappa and…
…turned to necrophilia? Sooooo much more colorful! 
Msmith001
welby.
Then, when I went on hiatus and came back and couldn’t remember by password:
welby1.
Then I got it changed back.
I signed up for the Dope using my stock username - blink178. Then I decided that I liked the place and wanted to stick around, so I had it changed to roadkiller. A while later I decided raz would be even cooler, so now I use that for most of my internet endeavors.
TubaDiva didn’t say anything about me changing my name twice. I believe she just said something like “Didn’t I just change your name?” and I said yeah, but I decided that I don’t like it anymore. So she changed it.
Trumpy, you can do stupid things!
Mine has always been the same. The first board I posted to didn’t have a lot of creative user names, so I just chose cher with lowest number I could get. When I started here I didn’t bother changing it.
Braaaaaaaaains…