For example, we have two apps:
1. Micro Fitness:
https://justfitness.io/
2. Micro Nutrition
We created Gym Tools:
https://gymtools.io/ in order to drive traffic to our main projects. So far the reception has been great! We're looking to add a newsletter form at the bottom to gather qualified leads. And also expanding GymTools to not only have a plate calculator, but also protein, macro, etc tools.
I'm curious what mini-SaaS and other mini-projects you've created to do the same :)