Teachable and Udemy are two of many, but these are the most prevalent, and they’re both intuitive and user-friendly. With Teachable, you have more control over your pricing and the look and feel of your course, but you don’t get a built-in audience. Instead you have to do all the marketing yourself. Udemy has a built-in base of students, but you don’t have as much control and they take more of your revenue.
Managerial accountants define residual income as the amount of operating revenues left over from a department or investment center after the cost of capital used to generate the revenues have been paid. In other words, it’s the net operating income of a department or investment center. You can also think of it as the amount that a department’s profits exceed its minimum required return.
Vanguard: Vanguard has a minimum of $50,000 and a fee of 0.3%. Rebalancing is done automatically once every quarter and tax loss harvesting is done on a client-by-client basis. We included Vanguard because clients who invest between $50,000-$500,000 have access to a team of financial advisors. Those with accounts over $500,000 will have a dedicated advisor.

Or you could do joint ventures/strategic alliances for your business or for other businesses and make residual cash flow for $0 investment.. that’s what I do lol. No money, no risk, little time, 20+ years working from home. Just connect companies and take a %, use the Internet to do it locally or globally, be the intermediary & connect companies…. ;-)
If you're looking to get started in real estate, look at a crowd funding solution like RealtyMogul. It works similar to LendingClub - you commit as little as $5,000 towards a property. When the property is fully funded, you become an owner, and will receive your share of the earnings and appreciation in the property.  Check out RealtyMogul to learn more.