What is the best way to keep tomcats from spraying your yard which does not involve keeping a dog?

There are quite a few tips on the internet but a lot of them (like putting mothballs in your flowerbeds) are toxic for the animals.
The most reasonable tip seems to be planting the Coleus-Canina plant (also known as "pee-off-plant)- that has a smell cats dislike- around your garden.
For more tips read this article
www.elkgrovecity.org/
animals/
printables/
keeping-them-out-cats.pdf (it wont let me post the proper link: One or more of your words is too long.
Did you forget to add a space somewhere? hmmmpf)

I've heard that used coffee grounds (sprinkled around the target area) can help.

I also recall growing up in Hawaii that folks would fill up glass jars with water and set the jars around the yard. My understanding was that the light refraction freaks them out. But I don't really know if this also works for cats or dogs or if it even works at all.

I found this article on snopes about this practice. But snopes says there's no definitive study about the efficacy of this method:
link

you should scatter orange peel around the target area- cats cant stand the smell. it always works for my gran.

basicly use the same method to keep cat from scratching your furniture... regularly spray a cirtrusy smelling cleaner or watery substance around your property (cats hate cirtrusy smells) Or teach your cat to walk on a leash and harness so you can moniter what shes doing out side and you have a little control over what shes doing.

spray your lawn with orange and lemon juice.cats hate the small and its good for your grass.