So, it’s like the 7 Deadly (S)Incomes? Ha. Bad joke. I never really thought to count them up or even name them but I’m a big fan of having multiple streams of income. Let me count. 1) Earned income (freelance pharmaceutical copywriter) 2) Royalty income (published book) 3) Interest income (savings accounts) 4) Business income (my personal finance blog) 5) Pension beneficiary (RIP daddy) Crap. Only five and only 1 that pays anything substantial. Hmmmm. Time to brainstorm. Thanks, Doc.

Another benefit of investing in rental properties is the loan pay down. If you obtain a loan to buy the property, each month your tenants are paying off part of the loan. Once the mortgage on the property has been paid off, your cash flow will increase dramatically, allowing your mediocre investment to skyrocket into a full-fledged retirement program.
The goal of creating multiple income streams should be to maximize your potential in each category available to you.  If you are just starting out, it really isn’t reasonable to expect you to generate tons of rental income.  However, if you start maximizing your income generating potential through your primary salary, you will find yourself having excess income that you can reinvest to generate additional income streams and earn more money.
Nice list. What keeps my family from getting more streams is the time it takes. I would actually be willing to work part time in medicine and make less money with a side-hustle just to keep things fresh and prevent burnout. That requires some degree of FI and some time to read about the new endeavor. Maybe when my kids are both in school, we we see. Until then, I’ll keep reading your posts for ideas.
If you happen to be a photography enthusiast, consider selling your photos to stock-image websites like Shutterstock, Alamy, and iStockPhoto. The demand for high quality pictures in commensurate with the competitiveness of this business. So, if you find a niche (such as landscape photography or business photography) and establish yourself as an expert in it on even one site, you can certainly earn a lot of money in your sleep.
In equity valuation, residual income represents an economic earnings stream and valuation method for estimating the intrinsic value of a company's common stock. The residual income valuation model values a company as the sum of book value and the present value of expected future residual income. Residual income attempts to measure economic profit, which is the profit remaining after the deduction of opportunity costs for all sources of capital.