Tolerance
From Metafilter:
Test your Hidden Bias. Tolerance.org has a set of Java-based tests designed to shed light on personal hidden biases w.r.t. race, gender, sexuality, and body image. Your results may surprise you. See also this New York Times article mentioning these tests and more rigorous studies.
I worked briefly for Tolerance.org's parent, the Southern Poverty Law Center, the producers of Hate Watch. It was quite the learning experience for me at the time. It's too bad they don't have a Spanish translation of this.
-Russ