For the three-year-old: dress-up clothes? Like a ballet tutu, leotard, and tights?

For the one-year-old: Every one-year-old I've ever known has loved a particular toy where you put balls in the holes on the top of the gizmo, whack them with a hammer, and watch them spin paddles and rock levers and so forth as they go down to the bottom - something like this. This will not help you if the one-year-old in question has this toy already, of course.