Mechanical Turk: Amazon's Mechanical Turk is a resource for doing human-intelligence tasks, or as the site commonly refers to them, HITs. You get paid a very small fee for any given HIT and you'll need a good deal of volume to make a substantial amount of money. But it is a resource you can use in your spare time to generate a small income online.
Become a proofreader. All kinds of businesses hire professional proofreaders to look over their copy and content for errors before they publish. This side hustle is one that could work for nearly anyone since you can work from home provided you have a computer and an internet connection. You can find online proofreading jobs through websites like Indeed.com and FlexJobs.com
If you’re looking for inspiration, my friend Michelle Schroeder-Gardner of the website Making Sense of Sense has become the expert on all things affiliate marketing. Michelle earns more than $100,000 per month from her blog and the bulk of her income comes from affiliate sales. Michelle has had so much success with affiliate marketing that she even has her own course called Making Sense of Affiliate Marketing.