Have an extra room in the house? Try renting it out on Airbnb.com. According to Smart Asset, you can pay up to 81% of your rent by listing one room in a two-bedroom home. If you're really looking to ring in the cash, renting out a private home or apartment is the way to go. According to Smart Asset's findings, rates for full apartments are significantly higher than those for just rooms, with annual profits ranging from $15,000 to $31,000 for a two-bedroom apartment.