Via the glorious Wikipedia, here's a nigh-exhaustive list of ethnic slurs -- perfect for your next trip outside the lily-white trailer park that you call home.

My favorite: "Wonder Bread Wop -- U.S Italians; an Italian that acts white (does not make home-made pasta, did not grow up in italian neighborhood, does not have accent or does not use Italian-American slang, etc.)."
List of ethnic slurs - Wikipedia, the free encyclopedia