I've always been Kelida (pronounced ke-LEE-da, just in case anyone out there is mispronouncing it as kel-EYE-duh) because that was the name of a character in a fantasy book I read once, and it supposedly meant "wanderer" in Dwarven, or some such nonsense. In any case, somehow it stuck, and I've gotten a bit attached to it now.
For my passwords I sometimes use compounds that I remember from Chemistry, mostly because they're easy to remember and a good mixture of letters and numbers. When I'm feeling lazy I just use my student number from school plus my initials. . .