I would say that record keeping and verification may be a good use of nostr, such as using a deed or receipt note kind. That's an interesting idea. Provable sales and such would be cool. 

 There is a draft NIP out there for contracts.   https://github.com/nostr-protocol/nips/discussions/752 

 Freaking sweet! Eventually, I'll have to a actually read all the NIPs to know what's already been thought up and may already be in development.