Do you mean hobbies where Ne/Si or Se/Ni work together in tandem?
I guess genealogy might fit Ne/Si working in tandem. I know Si types who like genealogy becausee they like the historical, nostalgic aspect of it. Discovering family traditions and heirlooms and making sure they get passed from generation to generation. It also involves alot of attention to detail. You need to be accurate about your facts- the spelling of the names, the birth dates, etc. On the other hand, genealogical research involves a lot of Ne. Sometimes it involves alot of creative searching to track down that elusive relative. You sometimes have to be open to alternative approaches. I know one genealogist who says the search process is addicting, you keep discovering more and more tangents and directions you could further pursue your search (more Ne).
I can't come up with a good Ni/Se example right now.
5w6 or 9w1 sp/so/sx, I think
Ni and Se. Two words. Video games. Ni, being a function that is best used for cognitive problem-solving, is great in video games. Ni can be very quick in deciphering strategies and turning them into hunches. Se is more of the indulgence factor. Of course, video games could be an Ne and Si thing, too.
Of course, it might just be that way for primary Ni's.
Most hobbies/activities draw on the use of a combination of cognitive functions and perhaps work through the hierarchy from dominant to inferior but some examples that the Ni-dom/Se-dom/Ne-dom/Si-dom types generally find very stimulating:
Se - activites that involve a high degree of sensory/body awareness i.e. sports, dancing, video games, driving/motorbiking
Ni - activities that involve conceptualising an idea or speculative theorizing
Ne - improvisation activities
Si - maintenance or routine-orientated work