I clean up the grass area on the side of the yard that my neighbor's and I share. I also blow off most of their driveway while I am at it. They never thank me but they don't tell me to go away, either. I can't keep their leaves off my side of the yard so I clean up the entire side of the yard of leaves. But I also leave some leaves for them to rake, too.
I think if you can't or unable to clean your neighbor's yard for the sake of your own, I think blocking the leaves would be your best bet.
