We picked up one of those little pocket laser pointers that you use to point to things and it shows a little red dot.  They cat loves it!  Great way to give an indoor cat lots of exercise.  You point that around on the floor and he goes nuts.  Also good when you want to get out the door and he is hovering around it to plan his escape, just point that on the other side of the room and off he goes.  Since they are so bright, they can even help to attract and indoor cat back in after a carefully thought-out escape :)

Another cat we have which is mostly an outdoor cat does not seem to be so enthralled with it.

Of course, you should never point it at their eyes are anywhere near them!

PS: Found another use for these, playing with you fish.  Seems my goldfish think it is food and chases it all over the tank ;)