Posting unexpectedly from out-of-town. It helps one discover how much one hates the iPhone blogger app.
Yinyang, or yin and yang as we tend to say it in English, is the theoretical complementarity of opposites in Chinese tradition such as Daosim and Confucianism. It is famously recognized (though hardly ever correctly named) in the taijitu (great power diagram) symbol.
The symbol has been used in mythopoesis by author Robert Jordan. The symbol could be used by gamers who play with a three alignment system, especially one where they do not equate Law and Chaos with Good and Evil. Law as Yang and Chaos as Yin would make the taijitu the perfect symbol for Neutral alignment. I've been playing around a little for how I might use this in my Ygg setting. More to come on that, soon.