Some More:

Torso Kitty: Term used to describe when a cat sits so that its paws, legs, and tail are completely tucked under it's body, making it appear as though the cat has neither feet, legs, or tail.

Cat Ball: When a cat curls up in a tight, circular-like shape.

Cat Cluster: When two or more cats curl up together in such close proximity to each other that there is no visible space between them, making difficult to tell where one cat ends and the other(s) begins.