Yeah, or another dog... but I suppose you've already thought about that and rejected it.
My dogs (sisters) are very different in their choice of toys. Poppy likes those Audubon birds that call, especially the giant-sized chickadees.
Penny is totally attached to a large stuffed animals, about the size of a ten or fifteen pound puppy. Whenever she gets excited she has to find one & carry it around. Audubon birds do nothing for her, but she'll watch the squirrels in the trees outside for hours.
Another fun toy (though you have to surreptitiously and actively control it) is a laser pointer.
Again my dogs react differently, Poppy is totally entranced... Penny is mildly interested. Here's an image, btw, of a cat named Poppy who also is interested in laser technology.
Poppy is so nuts about the little red dot that I have to let the light scoot outside the door and escape, otherwise she won't quit watching for it. If I just have the light go under a piece of furniture, she'll stay there and continue to watch for it for hours.