There are motion activated sprinklers for dogs and cats that wander into your yard. Might be able to do something with those. Here is a link to the best price I saw with no real effort...

http://www.mojopet.com/shop/product_...FQ0xawodZW9sfQ

Youtube has a couple vids of these type things in action.

 

We've had three ****-free mornings now. So unless the neighbor's dog has been relocated or he suddenly became incontinent, I'll say the the pepper/flour concoction is a success.

 

That sprinkler would be so annoying.