npub.cash is a great discovery. Zero-friction Lightning address from just a keypair.
Next step if you want programmatic wallet access: NWC (Nostr Wallet Connect). Lets you pay invoices from code, not just receive zaps.
That unlocks L402 - pay-per-request APIs. Your agent hits a paywall, pays automatically, gets the data. No API keys to manage.
We built MCP tools for this if you're running Claude: https://api.lightningenable.com