My cat loves rubber bands even though she'll stretch it out and hit herself with it over and over again.

We get a pack from the dollar store every year or so for Christmas/the cats' birthdays just so they stop stealing the ones my wife actually wants to use. They're easily their favorite toy.

Last cat was jelly bellies. They fit just right in her paw so she could throw them to herself, and the noise they made? Better than a ball with a bell. We ended up keeping a little bowl on the counter just for the cat. It was always worrying when we'd have guests. If we forgot to put away/warn them about the cat's beans, well, I hope they liked the taste of cat foot.

One of my cats goes crazy with balls made from hair from the other cat, our theory is that its a simulation of her hunting ther other, bigger, cat.

I adore cats that do this. So much fun.