I love these kind of posts. Here are some interesting ideas for side-gig:
- Books. There are quite a few books there, books for babies, books about iOS dev etc.
- Mining Cryptocurrency. This comment got a lot of attention.
- Apps. Too many but was glad to see Mac apps generating decent income.
- Music. Decent income from YouTube content ID payments according to this comment.
- DIY biologist. Seems fun.
- A lot of SaaS or content sites.
- Flipping items from thrift stores on eBay.