I got one of these yesterday:
http://www.petsmart.com/cat/shopping...%5F20155.shtml
And I think I'm going to need to replace the cardboard scratching pad in another day or two! Just about everybody's been playing with it--even Lily, who usually ignores the toys. There are little bits of shredded cardboard all over the living room now, but it's well worth it to see the kids having so much fun.