Acceptable methods of revenue generation

I want to introduce the activities that I consider acceptable for generating revenue towards the £10k per month aim at EarnMoreThanBefore.

1. Affiliations
2. CPC advertising
3. CPM advertising
4. Commission on referrals
5. Using additional websites to gather more interest
6. Sales at stock agencies
7. Sales at Print-on-Demand services
8. Commission for remote bespoke creative work. If I have to attend in person, then it doesn't count. This is online only.
   
9. Sale of websites (although hardly likely to help per month unless it becomes a regular activity)
10. Reviews
11. Hubs & Lenses
12. Information articles on other sites

I'm convinced that there are few additional methods that I've forgotten. I'm also convinced that I'll discover other methods. I'll list them here as I find them.