Marc Lehane wrote a blog article years ago around batching with limits/offsets which is always a fun assignment: https://www.mendix.com/blog/limits-and-offsets/
Our team developed a system for the international house at WPI to automate 'English Proficiency Test Management' process. There was a requirement to generate unique time slots for students. The slot was to be generated based on the date, testing laboratory available time, testing duration, laboratory capacity. We developed this functionality using a microflow which replaced a lot of manual effort.
Recursive Microflows are something you don’t see a lot, might want to add that to your list.
The execute stuff from Core is also interesting, especially the async and transactional stuff, check it out
Deeplinks, validation microflows, microflows heavy on client interaction, data synchronisation (after offline-online sync, webservice update or excel import for instance) are some examples of patterns/microflows that occur often