I have down a lot of side gigs in my life. Currently I have a few people that I dog sit for. I either watch the dogs at my house or stay at their house when they are away, if they want me to take care of other things while they are away. It's pretty easy money, and I usually bring in about an additional 200.00 a year. It's not a huge amount, but something I enjoy.
I also played baseball in college, and was giving private baseball lessons. I had all my own equipment, from batting tees, to catchers equipment, hundreds of balls etc. At one time I was giving lessons to three different kids making an extra 150.00 or so a week. It was fun, but then I got nervous about a kid getting injured, and getting sued. I stopped as my clients got older.
When I was a teenager, I used to mow lawns. I had about 4 in my neighborhood. Most of my current neighbors pay about 100.00 for professional lawn services. I have been thinking about getting back into lawn care again, and charging 75. LOL