Imam Jafar as-Sadiq once said, "If you see something you don't like in a brother, try to find 1-70 excuses for him. And if you can't find an excuse, say 'There might be an excuse, but I don't know it.' "
This is a quote that I believe would stop a lot of the suffering in an Ummah that otherwise has worse problems to deal with than back-biting and prejudice. These two things slow our progress as a community and can be easily stopped or slowed on a personal basis.
I understand that I am not immune to the behavior the quote above is about, and that is why I am speaking to myself first and foremost. I hope to cut down and stop my own prejudices toward others, and I hope that others will do so as well. Not just in my local community here, but also across city, state, nation and continental boundaries. We are an Islamic Ummah, not any particular Islamic nation, race, tribe or circle of friends.