We got a "Go Dog Go" that is similar to this contraption http://www.buygodoggo.com/ . Unfortunately our incessant ball dog (German Shepherd-like thing) won't drop it into the bucket! I don't think he trusts it.
This one looks good for 'dem smaller in stature dogs!
Hey, sticks and stones baby. And maybe a wee mention of my stuff:
change the world (for the better) with hands on permaculture