My cat love the Petsport Laser Chase II.  Well 1 of my cats do, the other is to lazy. 

Most of the time my cat (Larry) will chase the laser as long as you can keep moving it around, she does need a break for time to time because her heart is beating so fast.  After a few seconds, she is ready to go again.  The Laser Chase II is a great item to buy if you have cats, because once they catch other toys, the fun is over.  They never catch the laser, so the fun just goes on.