1. Apartment: Many newer homes have an "in-law suite" or apartment built-in. And many folks don't use these apartments or use them as play rooms for the kids. Renting out the in-law apartment is a good way to bring in as much as $10,000 to $15,000 a year, depending on where you live (perhaps more). That would be enough to buy a new car every year.
2. Vacation Rental By Owner: If you live in a vacation destination area, and you do not occupy the home full-time, consider renting your home part-time on a site like VRBO. We did this with our condos and made quite a lot of money. And you'd be surprised sometimes, where people will rent. If there is a local college or university nearby, parents will rent homes for commencement week or for parent's weekends, etc.
3. Home Office or Business: If you run a business, consider running it from home. Or, if you own a business, consider moving your home there. A friend of mine has a small factory that he owns, on 20 acres of land. He rents a house for his family. Why not put a modular home on the 20 acres of land, and have no mortgage or rent payments? I paid for office space in Old Town Alexandria, until I realized that I could use my home as an Office, and save tens of thousands of dollars a year in costs. Some folks run bed and breakfasts (which can be a lot of work) from their homes, if they are in a resort area. You are only limited by your imagination.
4. Storage: Do you have a barn or garage you are not using? Boaters and car collectors will pay money to store vehicles in such structures. Don't let that space go to waste!
5. Roommates: If your home is not set up to be readily reconfigured with an apartment (or zoning laws prohibit this) you can still take on a roommate. Granted, there can be difficulties in such arrangements, but the potential income can be huge. If you configure the home so the roommate has their own bathroom and kitchenette, you may end up never seeing each other. And in transitory areas, like college towns, a roommate may only be for a few months, at most.
6. House Swapping: There are online services you can use to "house swap" with people from other parts of the world. You fly off to England and enjoy a house in the Cotswalds, while they come to your beach house for a summer vacation.
7. Divide and Conquer: My office building in Old Town had three levels of space. If I rented it out as one unit, I might get $2000 a month for it. But by dividing off the top floor as a separate office, I could get $1000 a month for that, and $2000 a month for the lower level. You get more for renting multiple smaller spaces than for one big one, as people usually don't need the larger spaces.