If you have a propensity for writing and you can slay with your prose, consider writing an ebook. While the market has certainly become saturated as of late, books that help teach people about a technical topic still sell extremely well. This is a great source of passive income but does require a large amount of effort at the outset before any money is generated.
To do that, you have to harbor a few fundamental guiding principles in your mind. Today, if you're at all serious about generating a full-time income (and more) from your online activities, then you need to focus on passive income as opposed to active income. Sure, the active income will help you survive. That's the scarcity mentality at play. But it's the passive income ideas that will help you thrive.

>> Article marketing and comment posting is also very effective method to promote your product for free on the web. Write articles about the product and publish in article submission websites including your affiliate link in signature. GoArticles.com, ArticleDashBoard.com, Articlesbase.com, iSnare.com, SelfGrowth.com, Buzzle.com, ArticleCity.com and hubpages.com are great websites to write article for the promotion of your product. On other hand posting comments on blogs including your affiliate link in the URL field can also give you free traffic. The more time you spend the more sales you can make. 

Thanks! I have a few products mixed into my blog posts, and will be adding more. I have found CB to be a mixed bag so far – but need more time to see how it pans out. Also wondering about setting up more sites to follow the funnel you set up. I was pleased to hear you mention having 3 follow ups in the responder sequence. Someone else had suggested 10! I figured by 4 or 5 you lost them anyway.
My situation is I’m a Professor and Program Director for a Community College teaching massage therapy, a very in-demand field yet my college does little marketing. It’s my job to recruit students. I have a Facebook page and Twitter, and about 100+ followers on each. Can you see this type of system with funnels etc. working to help recruit potential students? If so, how? I feel like building content and creating opt ins should help, as we too are offering a “product”. Thanks for your time!
Buy and sell domain names. If you’re good at finding popular yet undiscovered domain names, you can make some cash on the side by buying and reselling websites. Think of it as digital real estate speculation. Domains are available on GoDaddy.com for as little as $2.99 per year, but are sometimes resold at far higher prices: According to Business Insider, the site MM.com sold for $1.2 million dollars in 2014. Once you find the perfect domain name to resell, you can market it on Flippa.com for a flat fee.
Double check yourself, before you double wreck yourself. Make sure everything you send to a company, whether a résumé, an email or a portfolio, is good to go. Double check your grammar and wording, and for God’s sake use spell check! This is especially important when it comes to the company’s name. Don’t spell their name wrong and be sure to type it how they type it (e.g. Problogger, not Pro Blogger).