From the TV show "Joan of Arcadia". The term is used when a person's actions (however small) end up having a positive outcome. 'Good Ripples' are felt in just about every episode of the show as God asks Joan to do small or big tasks which sometimes seem to her to be pointless. Joan doesnt always see the positive effects of her actions, but that doesnt mean they arent significant.
The best use of 'good ripples' was in the "Joan of Arcadia" episode 'Jump' 112 -
JOAN: the ripples were good
HELEN: very good