Also popular, according to sf/fantasy writer Cherie Priest, who often features her cat on her blog, are penlights. Not the pen itself, but the spot of light you move about on the wall or floor.
Today I had lunch with Psynde, who brought Spain the Cat a new toy: A laser pointer with rotating wheel of pictures. She can chase a butterfly, a star, a smiley face, or a mousie. At the moment, the butterfly is the big winner. I wore her out playing with this thing for over an hour; now she’s sacked out on top of her cat tree, snoring like a goose with a harmonica.