Teaching Tolerance is an amazing education project by the Southern Poverty Law Center. They have designed lesson plans, classroom management guides, curricula, and games that promote understanding and tolerance. All of their resources are available for free, either online or by mail.
Last year my elementary students became obsessed with Rosa Parks after seeing Mighty Times: The Legacy of Rosa Parks. The video comes by mail with discussion idea and lesson suggestions. Also, there are more suggestions on their site for teaching with this documentary.
I Will Be Your Friend is a book of "songs and activities for young peacemakers." A cool example is "1492" which cheerfully re-examines popular beliefs about the discovery of the Americas.