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.
Or you can take dog walking a step further and get paid to take a dog in while the owner is away! Have you ever checked to see what it costs to board a pet? Those places are not cheap! Do some research and charge 10 – 20% less. Plus you could post your ads on Craigslist or around town. But don’t expect people to just leave their loved one with a stranger. Make sure you offer your references and that you have all their necessary information if Fido gets injured or sick. Rover can help you here, too – Become a Pet Sitter.
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).