Growing a Nep as houseplant also depends on your location. People in places like southern florida might be able to grow N ampullaria, N bicalcarata, and N gracilis in a bright area of the house, although they probably wouldn't grow too quickly there. Alternatively, people around washington and oregon could get away with having a few highland Neps as houseplants (I think unknownclown has most of her neps growing that way).
The "perfect" nep houseplant where I live (Puerto Rico) would be on of the more shade tolerant neps such as N longifolia, N ampullaria, N bicalcarata, N northiana (maybe) and N adnata (maybe). I haven't actually tired to grow any of these plants as houseplants, but when I have the oportunity I'll definitely try.
Jœl