Leave it to a lazy guy to figure this out!
While I love to squash the "jumpies" and splat the "sheep", I simply HATE having to wait for my page to refresh to "play again".
I found that, at least with a Mac, if I just click on the frame of my browser window (Netscape OR IE) it will stop the animations as long as the mouse button is being held down. Let it go and they start up again!
Does it work for you PC people out there?