Working from home has a lot of advantages, a better work-life balance, no commute, and more time for doing the things you really love. It looks even more attractive when you think about what modern work is becoming, what with zero-hours contracts, the gig economy and wage stagnation.
The following question on Quora says it all:

How can I make around $80 a day on the Internet to start working from home and quit my day job? I'm 19, I hate working my day job and working from home has always been a dream of mine, any suggestions you guys can throw would be great.

The answers the 19 year old got were pretty good, including:

I would extend the above list with the following:

Let's now take a look at these options, to see if any of them can actually be used to generate any actual, real world, money. Before we do, however, we should take a moment to remember that what works to make money on the Internet is obviously going to be different for different people. Some people, people with craft skills and creative personalities, can make a good living from Etsy, for example, while others just won't be able to produce the kinds of products that customers on Etsy find appealing. I don't have the fine-motor skills required to glue-gun all he glitter and fiddly bits in place that make appealing Etsy products, so I never managed to make any money through them. Just because I don't recommend it doesn't mean it isn't a good site, and just because I do recommend a site doesn't mean other people will ever manage to make any money out of it.

Another caveat is that I have tried all of the options on the above lists at various times, with various amounts of success, and none of them have come anywhere close to replacing the money I can make in my day job as a language teacher. I have, though, managed to make some very useful money that, when you put it all together, amounts to a nice side income. Let's start with e-commerce, which is probably the option I have had most success with.

E-Commerce

For me, e-commerce means creating role-playing games to sell at RPGDriveThru and working with my partner to do vector graphics to make nice designs for t-shirts, which we sell through Society6. If you follow the RPGDriveThru link you will find a collection of PDF's that I have authored, many of them relating to the Cthulhu Mythos and 3D spaceships. It's very nerdy stuff but it's one of my passions and I have made a few thousand dollars over the years from selling them. The Society6 designs are more fun and appealing, and they have generated a few hundred dollars.

Web Development

I have created a few websites from scratch, including HTML, Wordpress and Hugo, but I never made a single cent with web development. The problem is that web development is hard. Web development is something I have learned because I had to, not because it was a passion, and I don't believe I could offer a customer the perfectly crafted solution they would want. One of my Wordpress sites even got hacked once, a terrible experience that I doubt I could have handled if the site was a commercial product I was running for a customer.

Elancer

I have created products for customers, mostly graphics and 3D models, and this has earned me, maybe a hundred dollars, all together. I found my customers through Deviant Art which is a fun environment to be creative within, but there are too many sellers and not enough buyers. I'm trying to avoid my day job, but it is possible to become a language teacher via the internet with sites like Verbal Planet, which is something else that I have tried, and something else that does not come close to replacing a proper day-job income, as a language teacher in a bricks and mortar school. It has made me a couple of hundred dollars though, over the years.

Affiliate Marketing

This a blog post I wrote where I include an affiliate link to a comic book. For me, this is the very definition of affiliate marketing. I like the product, I recommend it and provide a link. If somebody follows the link and buys the comic book, I get a little bit of money. I never managed to make more than a few cents with this way of making money on the Internet. Of the affiliate schemes I tried out, Amazon was about the best for me.

Cryptocurrencies

The days of being able to make any money with Cryptocurrencies are long gone, unless you invest in a warehouse full of supercomputers. I have dabbled with Gridcoin and made a fraction of a dollar, after weeks of my computer doing number crunching that sometimes slowed it to a crawl. I would still recommend Gridcoind because it uses home computers to calculate useful equations, such as the ones needed by SETI. Some people even do it for free. Just don' expect it to make you any real money, like say enough to buy a coffee with. I would include Steemit in this category, but this is my first post so I have no idea if it is possible to make any money or not.

3D Model Making

I love creating 3D models, though I am not a detail-oriented enough person to do all the many little things required to make my models compatible with video games. My models tend not to have texture maps, for example. Even so, I have managed to sell a few on a site called Turbosquid, for somewhere in the region of a hundred dollars, over the years. I can imagine that somebody with time to dedicate to 3D modelling could make a lot more, and you get to say that your job is as a Spaceship Designer.

Google Ads

Google ads are one of the first ways that I thought of to try to make the Internet make money for me. I have made a few hundred dollars this way, though not any time recently. Making money with Google Ads requires a huge amount of dedication, to learn SEO and get as many eyes on your ads as possible. I got quite good at it, but I was reluctant to write anything about subjects that are really high traffic, such as getting out of debt, sex, cheap medication and such like. I always wrote about the things that interested me, such as monsters, sci-fi and spaceships. If you don't write about things that apply to virtually everyone - sex, death and debt - there is a natural limit on the amount of money you can make, and, in my experience, a quite low limit. My blog still has Google ads, but they only make pennies now because I'm not dedicating my life to feeding them eyeballs.

Desktop Publishing

I write books, sci-fi and fantasy mostly, and it has started to make some money for me. I'm having quite a bit of joy selling ebooks from the Smashwords site at the moment. The best thing about it, though it has made me only around a hundred dollars so far, is that once the book is out there, it is out there for ever. All I have to do to generate interest is write another book. Of all the options on this list, I think writing ebooks has the least drop off in sales if, for some reason, you can't dedicate time to promotion for a while.

As you can see, adding all my activities together, I have created quite a nice side income from doing things that I love. I'd encourage anyone to try a few things from the list and see if they couldn't do the same. It turns out you don't have to quit your day job after all.