I also have one tied to a manufacturing database at my company. When a batch of products rolls off the line I get an updated count of units made. Kind of a way to know production systems are running and there are no problems at the work cells.
I also made a rickety-ass system that scrapes the local commuter rail API and fires off a notification when one of my trains is late or cancelled. That's been pretty helpful. The rail company has a Twitter account, but I don't go there anymore. So I rolled my own.
ntfy makes this all incredibly easy. I love it.
They are receiving Sferics on the lower HF frequencies and tag them with GPS timestamps (with the PPS signal they are in the Nanoseconds precision range). A central server will then do the triangulation.
All with off-the-shelf hardware (STM32, etc.).
Their service is stable for many many years now.
(Offtopic: The STM32H7 ADC is great for many many things)