Is a meta-sodium sulfonate group on a benzene ring electron withdrawing or donating?
As $\ce{SO3H}$ is a strongly electron withdrawing group, I'd say that $\ce{SO3Na}$ is basically the same, but to a slightly less extent. The reason for this is that being a group of highly electronegative atoms both groups have strong inductive electron withdrawing effects but they are both at donating electrons via conjugation (only possible from $\ce{S\bond{2}O}$ bond). This means that the sodium sulfonate group will decrease the electron density on the aromatic ring.