Catholic Information Center on the Internet
Cardinal Joseph Ratzinger calls ethical relativism "the central problem for faith today."
Ethics Updates: Relativism and Pluralism
Web links; literature survey; and some questions to ponder and discuss.
Is Morality a Matter of Taste?
An article describing the philosophical justification for rejecting purely subjective ethics.
Objectivity and Truth
paper by Ronald Dworkin (published in PPA). "Is there any such thing as objective truth in ethics or aesthetics?"
Stand to Reason Commentaries -- Ethics
Many of these refute relativism.