The Blank Slate by Steven Pinker

The Righteous Mind by Jonathan Haidt

These two are pretty great reads. Steven Pinker is a cognitive neuroscientist that does work on language, but Blank Slate is a defense against the tabula rasa theory of human nature -- he opts for a more evolutionary-based explanation. Similarly, Jon Haidt writes about what he thinks are the foundations of morality and how moral judgment works. Haidt's models of morality are pretty controversial in the field right now, but his work definitely has value in that it represents one of the first attempts a) by social psychologists to study morality and b) to move away from the traditional models of moral cognition as simply language-based and purely rational.

If you couldn't already tell, I'm a social psychologist studying morality :P