Do we already have a drop-in replacement for (re-)captcha, but instead of a puzzle/checkbox you paste an eCash token into a field?
Discussion
Could even be a service you sign up to with your npub, and the service periodically DMs you eCash back that comes in via the form, or pays you out via lightning.
Ah! A rEcasha
Why not a rePoWcha while we're at it?
RPOW! 