I completely sympathize with your situation, because we have so many cats in our neighborhood that like to come into our yard to climb up our trees so that they can sit there and taunt our dogs (We have 3 hound dogs that just cannot resist the little buggers). Then, the cats' owners get all mad at us because our dogs bark at THEIR cats!! We actually had to go to court over it and pay a $468 fine because our dogs were barking in the middle of the day (not even at night).
I had tried yelling at the cats, throwing things at them, etc., but I finally got fed up with it and took out the slingshot. I use dog food pellets as ammo that won't hurt them but do sting enough to get them moving. If this doesn't work, I'm resorting to my father's method (he has a koi pond and the neighborhood cats like to hang out in his yard, poop and go fishing despite the electric fence and automatic sprinkler deterrent system that he has set up): set out a live trap (it doesn't hurt them), and then when you catch one, spray paint the tail (with nontoxic paint of course... the kind they use for livestock). When the neighbors' cats start coming home with neon orange, blue, green and pink tails, their owners get the message. He had a neighbor complain, and his response to him was that he had asked him time and again to control his animals, and that if the cat had not been in his yard, it wouldn't have been painted.
And as far as the people who say that this isn't cats... wake up. I am a cat lover, but of inside cats who are well behaved. I have no patience with people who let their cats run all over the neighborhood making trouble.