The Sims for Kids
Since this is a Nintendo game, however, unlike the Sims, the interactions which occur between people are highly structured and designed so as eliminate any potential of, ummm, more interesting interactions. It is a game designed for kids, although as an adult I certainly can appreciate its fairly interesting gameplay and design.
As for the online aspect, again, it is highly structured - and could be so much improved if it allowed for more potential interactions with "strangers" from other lands. This is not quite a WOW MMO, but is a rather good start toward an MMO type of community for Nintendo.