If you want to clear some space out in your house and have a big stack of books you’ve been holding onto for too long, you can make money selling your books and textbooks online. Stores like Half Priced Books and others will give you cents on the dollar for each of your current books while you can check what your book is worth by simply entering the ISBN number on Book Scouter.

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.
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.
Starting a podcast, like making a YouTube channel or blog, comes down to telling interesting stories and building an engaged audience. I’m probably sounding like a broken record by now, but you need a niche that you’re interested in and there’s already a demand for. Come up with a list of topics you’d like to talk about and then search iTunes charts, Google Trends and other podcast research sites like cast.market to see what’s currently out there and popular.
If you upload photos of yourself, or friends/family with consent, it's worth going for the 'rights managed' licence option – otherwise you'll have little to no control over how your images are used (eg, you could star in an ad for haemorrhoid cream). See Alamy's page on understanding stock image licensing for more on the different types of licences.
^{Whether you have a website or are still dreaming up ideas for a blog, you can also look into affiliate marketing. With affiliate marketing, you partner with brands and businesses within the content of your website. If you mention a product or service, you link to that produce or service using a unique affiliate code you received when you signed up for that particular affiliate program. From there, you’ll make money any time someone buys a product or service through your link.
The best part about this is that you don’t even have to ever touch the actual product, nor do you have to spend a dime on manufacturing these products. They do all the work for you. You just upload the design, choose the items you want your design to be on, and they’ll handle the rest (i.e. manufacturing, payment, shipping, and handling, returns…).}
_{Prior to that group, they had an online community for teachers looking for lesson plans. That probably sounds pretty random, but it's crazy the type of communities you can build and rally people around. If it's something that you're passionate about yourself and you want to connect with others that have that same passion, then an online community is something you should definitely consider.}
^{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.}
_{With the Discover it® – Cash Back you’ll get a generous 5% cash back on select categories each quarter you activate ($1,500 max spend), 1% cash back on all other purchases and no annual fee. Discover will also match the cash back you’ve earned in year 1 and provide you a 0% intro APR on purchases and balance transfers for the first 14 months (then, the regular APR of 13.49% – 24.49% Variable applies). Read review}
Using a food delivery service can’t necessarily earn you money, but it can help you save you money if you constantly find yourself throwing out half the food you buy. Food delivery services send a box of food every week with new, sometimes unique vegetables, meat, fruit, and so on. If you don’t have time to shop and want simple meal-prep that leads to a good meal, a food subscription service may be perfect for you.
Blogging is something that requires patience, persistence and discipline. It may mean writing everyday for over a year before you really start to see any money from it. There are exceptions to the rule, but from my dealings with other bloggers, it seems to be pretty common to spend one or even two years building your blog, your brand and your authority, before making any serious amount of money.
_{Using a food delivery service can’t necessarily earn you money, but it can help you save you money if you constantly find yourself throwing out half the food you buy. Food delivery services send a box of food every week with new, sometimes unique vegetables, meat, fruit, and so on. If you don’t have time to shop and want simple meal-prep that leads to a good meal, a food subscription service may be perfect for you.
You'll also need ecommerce software, fulfillment software, worry about warehousing, customer service and refunds. But that's not all. You'll also need traffic. Think search engine optimization, Facebook ads, and other social media campaigns. It is hard work, especially on your own. You could opt for Amazon's platform, which might be the easier route. But, then again, at the end of the day, this is a serious business, which could produce significant profits. So you're either all in or you're not.} 

Create a killer course experience: With your course validated and in the works, you need to figure out how people will take it. Most course creators choose to host their courses (after going down the path of learning how to make a website) on their own blogs. This way, they get all the value of bringing customers back to their site on a regular basis. I host my own courses from a subdomain on my own site so I can easily add more. The course experience is incredibly important as well. And after trying most of the solutions, I highly recommend Teachable—an online platform designed specifically for courses.