She's got an assortment of colorful balls, some catnip mice and a few other things, but her favorite plaything is string. That's it. String. Catnip, though at first gets her going, seems to bore her after a minute or so.
She loves chasing string, and we'll run around the apartment, trailing a 5 foot long piece and laughing as she trots and scuttles after it. And then she plops down. Sure, she'll swat and swipe at it if we're standing close enough, and once in a while she'll get up and come after it again, but I think we get more exercise out of it than she does.
She's also shown this interesting behavior where she talks and chatters at us, much the way she does when she's hungry, and leads us to her toy collection on her favorite mat.
She sits in front of her toys just looking at them, and when I start to pat her behind and scratch above her tail she begins to play with her things, sometimes going crazy rolling around and chomping heartily on her catnip mice.
Now, I've seen some of the videos and read a handful of articles about the whole cat spanking thing (there's an eye-opening amount of it out there), and it's certainly an interesting trait.
Orbit used to enjoy a hefty patting above his tail. My old pal Isaac loved a hearty smacking.