Neutral good characters desire good without bias for or against order. In 4th edition mechanics for Dungeons & Dragons neutral good is found under the umbrella of the good alignment.
A neutral good character does good for goodness' sake, not because he is directed to by law or by whim. Such a character will obey the law, or break it when he sees that it will serve a greater good. He isn't bound strongly to a social system or order. His need to help others and reduce suffering may take precedence over all else.
Luke Skywalker is a good example of Neutral good