I have to share my 'grandkitty's' favorite toy. My daughter rescued an adorable orange tabby when she was a poor college student. She made him a toy with a shoe string and a piece of aluminium foil. She formed the foil tightly into a ball around one end and tied the other end to a door knob.
His name is Virgil, and he is now 7 yrs. old and has a house full of toys, but his favorite is still the foil on a shoestring.