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.
Websites like Care.com connect parents with babysitters. The company does all the background checking and other due diligence to put parents' minds at ease. Of course, you can appeal directly to people in your personal network, but if you're looking to generate recurring revenue sign up with a site marketing to parents looking for child care services.
If you’re strapped for cash but want to work on your own schedule, you might want to consider becoming a driver for Uber or Lyft. You can drive as much (or as little) as you want and set your own schedule. Plus, you get the added bonus of having interesting conversations along the way (or, at the very least, some fun stories to tell of your travels with strangers).