Remote Controlled Mouse
If I were a pet toy inventor, I would definitely invent a remote controlled mouse for cats. I would also include with it a spray that had the "essence of a mouse," so the cat would be utterly convinced that it was chasing a "real" mouse. Since I also love dogs, they would need to have something cool to chase too. It could be a remote controlled cat, but I like cats and wouldn't want to encourage dogs to be chasing cats (especially not my cat). I'm almost thinking that a remote controlled rabbit would be lots of fun, but some people have pet rabbits too, so I'm going to have to stick with a remote controlled ball with extra thick plastic.
Reward: "For what's it worth" I'm sure my pet cat would appreciate one.