I think there's more to ethics than simply "do no harm." I think we have an obligation to make things better, and to alleviate suffering - and obligation for social justice covers it pretty well, although Glenn Beck might disagree. Yeah, I think I'd agree with Kendall that the Golden Rule covers it.
Most religions seem to have been founded on the Golden Rule, and often they spend most of their energy finding ways to prove that the Golden Rule doesn't apply to them....

-Joe-