I like to have my stay at home parents contribute to the household economy in some way. One is a freelance botanist and tending all those plants takes up quite a few hours. Another is a painter and sells her work form home. Another is a woodworker. For me, that is more interesting than cleaning and doing laundry. I haven't yet tried bee-keeping or flower arranging since I just purchased the Seasons expansion, but that is another thing I want to try.
One thing I would love to be added is some way to do homeschooling. I think that would be a good occupation for stay at home parents.