If you’re familiar with the phrase “don’t put all your eggs in one basket,” you know that it applies to just about any area of your life including—and especially—your finances. In addition to retirement becoming an ever-elusive goal, no one has guaranteed job security so by diversifying your income you can feel more secure about saving for your future. You’ll be less likely to find yourself in credit card debt and happier as a result of being financially secure.
That strategy seems waaaayyyy less risky than actively picking stocks of supposedly “reliable” stocks that issue dividends, which could be cut at any time due to shifting industry trends and company performance. Dividend investing feels like an overly complex old-school way of investing that doesn’t have a very strong intellectual basis compared to index investing.
If you’ve ever thought to yourself, “I wish there was a product that did this,” then invent it! Create a product, medical or otherwise, and sell it as a company or get royalties for it. It’s not impossible to figure out, I have many friends who have taken a concept to market. Don’t overlook an invention as a fantastic means of attaining passive income.
Index funds provide you with a way to invest in the stock market that is completely passive. For example, if you invest money in an index fund that is based on the S&P 500 Index, you will be invested in the general market, without having to concern yourself with choosing investments, rebalancing your portfolio, or knowing when to sell or buy individual companies. All that will be handled by the fund which will base the fund portfolio on the makeup of the underlying index.
No one should turn down wind farming’s ultimate passive income for the next 30 or more years … even 60 years when there is a positive cash flow on the sum total of all base payments when computing inflation for the next 60 years based on the previous 60 years, as long as the next era’s energy resource is not perfected (at which time they would not renew the option for the second 30 years).
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”. 

The idea behind cashback is simple: you get rewarded for purchasing or using products you plan to buy anyway. Cashback sites pay you when you click through them, go to retailers, and spend. For example, check out eBates.com - There are over 2,000 stores to choose from including Walmart, Target, Sears, Calvin Klien, and others. You also get a $10 gift card after your first $25 purchase. Sign up is free. (If you encounter a cashback site where it’s not, avoid it.
If you have specialized knowledge in a certain topic, you can put together an online course to teach others. For example, if you have experience in real estate investing, you can create an online course “Real Estate Investing 101”. The benefit of an online course is that once you create the course material, you can sell it to as many people as you want.