Job well done, Satrap. The first thing I look for in a site like this are signs that the author is being paid to hype the companies. It’s very tough to find good information that isn’t stricken with bias. There were a couple of times during the article where I actually got excited thinking, ‘Hey, I could do that. I’d actually LOVE to do that.” That being said, I can’t help noticing that you refer to all of it as “extra” or “supplemental”income. Are you saying that with all of these options, sticking to one’s regular “day job” is required? In your experience, if someone really commits to doing this, is it possible to earn a decent living? Cubicles suck.

29. Videos – This could be an entire section on it’s own. Many people have made money by creating YouTube videos. Evan of EvanTube is a kid and he has made millions by creating reviews of products that other kids his age would use. It’s not easy to get views into the millions, but once you do, you’ll start seeing some cash come in. Many bloggers have completely turned to videos to get their point across by starting a video blog.

First off, I’m a blogger so it seems wrong not to mention it, but more importantly, it’s a legitimate way to make money. It’s quite possibly the least straight-forward way on this list, but it’s very doable and it’s also quite possibly the funnest way on this list. I love blogging and I know hundreds of bloggers who feel the same. So let’s talk about making money blogging and what it really means.
Cafe Press: This website allows you to create digital designs that can then be sold on the platform. You'll earn a commission for everything that sells and you'll never have to deal with logistics like printing, warehousing and customer service. If you have some graphic design skills, then this is a great potential source for your web-based income. 
Earning by comments will require you to have your own Blogs and Websites. You will then share these dedicated domains (Owned by You) in the comment window. If an option to add your URL or website is not available, then you do not include links. You contact the site support first and get permission to share your URL. Oh, and NEVER share affiliate links in comments.
2. InboxDollars – InboxDollars is similar to Swagbucks, since you’re going to be taking surveys, shopping, etc., so if you want to maximize your return, sign up with both websites. They also offer a search engine that pays you (like Swagbucks) and you get $5 just for signing up.  I won’t continue to list survey sites one after another down the list, but if you want to get paid to take surveys, also check out GlobalTestMarket, E-Poll Surveys and Survey Club.
Once you really focus your efforts on one method and stop jumping from one thing to another, you will soon start to see results. And once you see results, motivation will take over from there and you will just keep going. The problem for most people is that they give up usually right before they see results. They work for a few weeks or months, they don’t see results, they give up and go for another method. They repeat this with any method the come across, and never make any decent money.
Clearly, there's a lot of demand on Amazon, and if any product is going to sell, it's going to sell well on Amazon. But the goal here is to source the right products that will easily sell at the world's largest online retailer. Generally, products between $10 and $50 sell very well here. Just be sure to do the right market research before jumping on this bandwagon.
VIPKID provides an international learning experience to children in China between the ages 4-12. Headquartered in Beijing, the company offers fully immersive one-on-one English language instruction provided online by highly qualified teachers. The curriculum is based on the U.S. Common Core State Standards and uses a flipped-classroom approach to foster creativity and critical thinking skills.
I’m using a free method as a result of my own researched to discover high value sites online for basically anything. The important thing is to tell Google what you’re looking for. Something like “Free Online Survey Sites That Pay”, then check page rank, and then both quality and quantity of visitors. You will find the article on how to apply this method on my Blog Titled – 2 Simple Research Tactics For Exponential Visitor Conversion At No Cost
28. Subscription – If you think of something valuable (newsletter, online magazine, etc.) that you can consistently offer on a certain basis (weekly, monthly, etc.), you may want to offer a subscription service. This could be a fee charged each time your product is sent out or on a monthly basis. Either way, this has to be something that your customers can only get by subscribing to your website.
Upwork: This website offers a great marketplace for selling just about any professional service. You don't need a merchant account, website of your own or anything else for that matter. All you need to do is be able to provide a high-quality service at a reasonable price. But be informed, you will have to compete with many others that are constantly bidding on open jobs. 
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).
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