NHF – new heroes for Heroes V 3.1.

What else, besides NHF, is in the data, UserMODs, and maps folders?

Nothing (well, there is something in data, but it's what should be there).

Added 10 minutes later
Actually, there is a GSC map – it can only be seen through the map editor, and not just by browsing the folders (using Windows Explorer or Total Commander) – that's why I forgot about it. I'll check when I get home (but it's a simple GSC map without any fancy features).