A market for alerts? 

The legendary nostr:nprofile1qqsgk539zq9ercdt86rv5r3qnzarmsyca4gnuc7d728p5cq05q9xkrgpp4mhxue69uhkummn9ekx7mqpzfmhxue69uhk7enxvd5xz6tw9ec82cspzamhxue69uhkummnw3ezuendwsh8w6t69e3xj7s84kuwj knocked an app together. 

I use it regularly to get an indication of fees.

It's obviously not using my mempool but it's just an app.

https://i.nostr.build/vGsM2FnVfZTAlVYN.jpg