Finally, I figured out a use! It would take a lot of good craftsmanship, but you could probably put the guts of a mouse into a cat.
Tech-support: "Okay, now use the mouse to move the cursor..."
User:"But I don't have a mouse"
Tech-support: "uhhhhhhhh"
User: "Do you want me to move the cat??"
Heyyyyyyy, I'll bet there's a market out there for novelty mice... you can get mice in the shape of your favorite pets... dog/cat/whatever. Remember, I thought of it first!
Or, how about an... Optical Cyclops??