I found a sports kit with the following:
- Steering wheel
- Tennis Racket
- Golf club
- Baseball bat
- Cricket bat
Do any of these improve your control?
They will not make the controller sense the proper movements more accurately.
They exist to either make the motions easier to visualize (a-la steering wheel) or provide a larger area for gripping the controller in the first place.
I think it just give you right feeling. And maybe help you to hold controller better (if you never played e.g. golf). But, as I noticed in most games, it doesn't matter that much how well you move your hand (tennis, golf, etc).
They don't really improve your control much. What they do however, is help with the feeling of immersion.