I've had a decent amount of experience doing children's portraits, and the biggest factor I've found in getting consistent good shots is just getting the kid out doing something they enjoy. I get tired of all the "sit still and smile at the camera" pictures, they just seem overdone. But if the kid is out having fun, and engaged in what they're doing more than they are in having their picture taken, I've never had issues getting some good footage.
So to end my rant, what types of activities do people here use to keep kids engaged? Personally I like using horses or simple activities like painting, but what are some other good ideas?