My cats, like my kids - rarely seem to play with the bought toys and much prefer chasing some random piece of paper or something they find.
We had hours of fun with a laser pen - one of those ones that projects a light on the wall - they'll chase for hours or the reflection of a mirror or something shiny. Any of those fishing rod type toys but we had a 'feather tickler' and the cat ate all the feathers out of it and I'm not sure this was good for him so wouldn't by again.

Yes Wendy - this weekend will mostly be cutting and sticking - fun
Actually I'm putting the cats in the kids old playpen and I can put a bar across the top and dangle things off - this is what I did for the kids too -

How long do you think it will be before they learn to climb out the playpen (although they're not out the nest yet only 9days)
Emily