:-) Well, I'm not sure if this can actually be considered a toy or not... but our cat is happiest when there is a cardboard box to play with or climb into. I know I used to hear that kids after prefer boxes at Christmas than what was in them. My daughter always preferred the contents of the boxes, but not so with the kitty cat... she'll choose the box itself every time!
In addition to that, she likes the tracker balls in the tube "thingies"... not sure what they're called, and she likes a battery operated toy where a fake mouse tail scoots in and out. Never was much interested in the things the stores sell as "cat toys."