Well, my own site, I suppose (I built it twice from scratch with Rails and Stripe). Journalism, publishing, articles. It might be possible to attempt the Substack on Nostr idea or something along those lines if I abstract some things out. But then we get excited about lightning and zaps and bitcoin so how do you do that and what does it all actually mean in terms of servers and databases and running things and costs and time all the rest? All of these things seem like fun ideas at the start and then take up lots of hours and life energy, so have to imagine their lines properly first. Also, not sure on a conceptual level that "Substack on Nostr" is going to be a thing. The more innovative thing might be integrating BOLT 12 into Nostr, across the whole network, at the mostly decentralised protocol level, not as a site.