Enhancing Human Traits: Ethical and Social Implications edited by Erik Parens (Georgetown University Press).

For those willing to plow through a fairly academic text (not too long) the rewards are a thorough review of the ethics of "cosmetic psychopharmacology" among other things, the fine line between treatment of a disorder and enhancement of a particular trait. Appreciating the "ethics of complicity" when it comes offering drugs or surgery for "empowerment." Why giving Ritalin to a child is not the moral equivalent to better parenting or schools for children.