As you may have noticed, the residual income valuation formula is very similar to a multistage dividend discount model, substituting future dividend payments for future residual earnings. Using the same basic principles as a dividend discount model to calculate future residual earnings, we can derive an intrinsic value for a firm's stock. In contrast to the DCF approach which uses the weighted average cost of capital for the discount rate, the appropriate rate for the residual income strategy is the cost of equity. (Learn the strengths and weaknesses of passive and active management when trying to uncover the overall market's worth. Check out Strategies For Determining The Market's True Worth.)
What are your thoughts on an Immediate Annuity as a passive income vehicle? I suppose it’s not a great investment since you never get your principal back, but the risk is zero and the cash flow is fairly good, approaching 6% currently. And, since you are guaranteed payments for life, you may not care that you never see your principal again anyway since you’ll be dead!

That income is considered residual income because as long as the apartment is rented and the rent is collected, the income is earned without additional effort. The effort came when the property was purchased and a tenant was found. Each month after that, the money automatically is paid without buying the apartment again or finding the same tenant each month.
How to Monetize: Affiliate marketing works well when you discuss products on your blog. For our fish tank blog, we would link to all the things you need to buy for an aquarium and then when people click on that link and buy that item (and other items they purchase with it with some exceptions) you get a percentage of the purchase. Amazon Associates is the best-known affiliate marketing program, but there are others like Impact Radius, ShareASale, Commission Junction, ClickBank and Rakuten too.
Whether you take a “distribution” (aka free-cash-flow) in the form of a dividend, interest payment, capital gain, maturing ladder of a CD, etc, you are still taking the same amount of cash out of your portfolio. Don’t fall for the trap of sub optimizing your overall portfolio’s performance because your chasing some unimportant trait called “income”.
Residual income is calculated as net income less a charge for the cost of capital. The charge is known as the equity charge and is calculated as the value of equity capital multiplied by the cost of equity or the required rate of return on equity. Given the opportunity cost of equity, a company can have positive net income but negative residual income.