In case you felt guilty leaving your cat alone, you can get another cat (and double your problems). Or you can clutter your home with cat toys that your cat will probably ignore completely. For another approach, you might be interested in helping fund Shru, a robotic cat toy shaped like an egg that’s programmed to mimic a living animal.
The idea is that you leave your cat with Shru and Shru moves around like a real animal to keep your cat entertained. Either that or your cat will be more entertained when you come home each day and find that the cat hasn’t touched Shru and therefore is mocking you for wasting your money on a toy that it never uses.