BESIDES digital marketing, content creation, copywriting, video production and social media management.
An example of what I believe to be "fun" B2B would be handling end to end for corporate events like showrooms, pop up stores and product launches.
Look for Amazon books with "Side Hustle" or "Work at Home" in the titles.
Amazon sells numerous encyclopedia style books, some with 100s to 1000s of ideas listed.
Creating ecommerce stores or online businesses can generally get super niche and can unveil crazy profits on occassion.
Look into things like
- Rank and Rent SEO
- Ecommerce Products
- Merch by Amazon
- Ranking a Consulting Niche Agency
Give me a shout if you need consulting on the SEO side of things, as I build Rank and Rent sites myself.
Cheers and good luck!