I once started doing a browser extension that would be a chat room, using the URL of the webpage as identifier to find and exchange messages through Nostr.

So, when you go to any webpage, the extension would query Nostr to see if there are any messages for that specific URL and present them in the extension chat room.

So that two guys on https://en.wikipedia.org/wiki/Randomness at the same time could have a random (!) conversation. 

 A few days ago, I saw a nostr extension project that allows people to zap freaks on youtube twitter, and github.