Tolerance.org
Tolerance.org is a principal online destination for people interested in dismantling bigotry and creating, in hate's stead, communities that value diversity.
I love this site! It provides a wealth of information, and additionally, you can order several DVDs and teaching materials for FREE! They say there is no free lunch, but these materials may challenge that. I also ordered a set of posters from which to teach. They were a nice addition to my classroom.
My favorite of all their available resources is "One Survivor Remembers," about Gerda Weissmann a Holocaust survivor... Pretty powerful, and can lead to so many different teaching avenues. If you teach history, or even a novel set during World War II, this teaching video and materials won't disappoint. They sent me a series of primary source materials (copies) of pictures, postcards, documents, etc. I hope that you take a peek!