Well, I'll tell ya. It's actually called a Critterbug Laser Light.
http://www.critterbug.com/ has the best pics, but plenty of sites have them for $7.99.
http://yorkietalk.com/forums/attachm...hmentid=&stc=1
There's also a video of a dog in action.
http://www.engadget.com/entry/8818248724858804/
This one is using an attachment for the iPod. I'm not really crazy about this gadget used with a pet. Looking at the light can cause eye damamge. But the video is kinda cute. The photographer must have worn this dog out, because they usually are more excited, ha ha.