Ball in the cup: Replace the ball with a firecracker and the cup with flint. The object of the toy is to ignite the firecracker by smacking it against the flint without blowing up your hand.
Haha. I make myself electornically laugh. Um. Nvm. How about a frisbee that has a propulsion system and is radio-controlled? It would be like a cross between a boomer-rang and a radio-controlled airplane.
Give me one more try. I know! Design a leap-frog iPad for kids. It would teach them the future of touch-tablet PCs, but wouldn't be so expensive for the parents. You could have learning apps.