NIP-42 (Client Authentication) enables an unlimited amount of client/relay user level configurability. Simple use cases include but are not limited to private/paid to read relays, restricting access to DM metadata for unauthorized pubkeys, personal private clearnet relays (without needing to restrict access by IP), and paid subscription relays (patreon).

More advanced possibilities include remote relay management for administrators, bandwidth/usage metering by pubkey, remote privatekey management, and many more.

If you are interested in contributing, check out our feature requests and bounties here: