I've gone through a boatload of usernames in my day, but currently I'm fine with Velocity. I chose it because of a silly fan-character I had at the time, who was a robotic velociraptor. It's something of a tribute to my favorite dinosaur, as well as simply a nerdy science word. On other sites, I go by VeloJello because Velocity's usually taken; everyone nicknames me Velo, I really like Jello, and they rhyme. Yup yup!