A couple of good books on the effect of television on behavior include The Plug-In Drug: Television, Children, and the Family and Big World, Small Screen: The Role of Television in American Society. I especially recommend the second book now that it has come out in paperback. This book backs up all of its recommendations with hard, scientific research.

Recommended listening again focuses on the Mozart Effect. Namely, the Mozart Effect emphasizes that music can positively (and negatively) affect our behavior and moods. Recommended healing music for the Columbine massacre is Leonard Bernstein's Mass and Mozart's Mass in C Minor.