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.

If you are a photographer looking to diversify your income stream, putting together styled stock photo packages can be lucrative. For example, a package of 15 wedding-themed stock photos for $10. You can then market this to any bloggers or businesses who are in the wedding business for their use (photos of different engagement rings styles are super popular). Through this method, it’s possible to make a continuous stream of income off of photos you’ve taken once (similar to a licensing deal).
I’ve never invested in real estate (except to live in), but am always intrigued by communities like FS who seem to have such a passion for it. My intrigue stems back to my earlier comments that the long term trends in appreciation in real estate are simply not very competitive versus equities, despite what Robert Kiyosaki had to say in his book, Rich Dad, Poor Dad.

Residual income is the amount of net income generated in excess of the minimum rate of return. Residual income concepts have been used in a number of contexts, including as a measurement of internal corporate performance whereby a company's management team evaluates the return generated relative to the company's minimum required return. Alternatively, in personal finance, residual income is the level of income that an individual has after the deduction of all personal debts and expenses have been paid.