Well, when I came on board as moderator--an offer that when Rebel extended it to me, it was a good thing I was wearing brown pants (given my then-reputation, undeserved I think, as a "loose cannon"), I was instructed that my job was to "grow" the forums I moderated, by always being engaged, by always interacting with members, by always posting stuff.
Quite different from the way dear old sweet Lu handles the cobweb-infested cooking and baking forum on Skins's island.
Unofficially, though, I suspect my job is to herd cats--but fortunately members are naturally courteous and considerate, and so herding cats isn't that much trouble, if trouble at all.