Another app that is using the custom json transactions on Hive in a creative way is 
Its a notification system for podcasts.
I have noticed these transactions are podping up in the top custom json operation and decided to have a look.
Here is the chart for 2022.
From the beginning of the year there was around 4k transactions per day and recently they jumped to around 12k transactions per day. Quite a lot.
I have looked what type of operations, content this have and there are few webs that come on top like feeds.buzzsprout.com, media.rss, feeds.transistor.fm, feeds.captivate, and many others.
Another unique use case for Hive :)
Might do a long form going forward.