When talking about morality I do like the yin yang symbol.
Obviously, my own interpretation of yin yang has been customized, and is probably much different then Taoism. For anything good (white) there is some evil. For anything evil (black) there is some good. However, these forces are obviously locked in a constant circular struggle, never quite able to vanquish the other. To me, this image fits well with my interpretation of good and evil. Though I try to defeat evil with good, I must acknowledge that evil is still an unacknowledged part of my person.
The true meaning of yin yang, however, appears much deeper and different than what I've written. Rather then opposing, White and Black are complementary forces. Though I'm no Chinese philosopher, it appears there could be a point there about morality as well. Let me know what you think!