I had a small etsy shop for the stuff I sew - baby blankets, neckties for little boys, superhero capes - but found that the hourly rate made it not worth my while, considering the fact that making the first cape is fun, but making ten for a birthday party is tedious.
Now I teach a couple of parent-and-tot music classes every week. Startup costs were minimal (bought some good-quality small percussion instruments) and there's virtually no prep time since I can lead a singalong in my sleep :) That brings in at least $65 for a 45 minute class (plus maybe 35 minutes of travel, so still a very decent hourly wage.) I've recently begun doing children's birthday parties. Around here parents will gladly spend all kinds of money on parties for the munchkins, so I make $100 for an hour's worth of songs and games.
This summer I'll be running a camp-type program for toddlers. I'm doing it mostly because I have a child that age and there aren't any programs that are appropriate, but also so that I'll make some money doing a lot of things I'd be doing with my own kid anyway: playing outside, singing songs, reading books, doing crafts. Also, most of the kids who are signed up live in the neighbourhood, so we'll be making new friends whom my kid can play with for the next 8 - 10 years. It should bring in about $2400 in profit for six weeks (only running two days a week.) That pays for day camp for my other two.
Have been thinking about an ebook, or maybe a Fiverr gig, but I don't have time at the moment. Maybe when my youngest is in school full-time I'll get started on that.