Black background with light grey text. Not pure white text because that can be hard to read too. If find the black/light grey a perfect combination. I find if the contrast is too high it is difficult to read, like dialyn said, it jumps around too much. Maybe have just afew option in colour scheme, and not change colours on individual things. Like have a normal scheme, blue scheme, high contrast scheme (for those hard of sight), whatever sheme.. that way you know all the text will be readable. :)