In which online services do users need to respond quickly to changes?

Question

Automation

I'm not sure what to write to the address, but the attempt is not torture)
Recently I came up with a script for an online investment service that parses information and reports on the limits that have appeared free for investment in this service. Notifications work on a paid subscription via instant messengers or via SMS (there you need to respond quickly, the limits fly apart). The people participating in the project became interested.
And I was puzzled by the question, in what other services can the paid mailing of notifications about some internal events be relevant? Please help me with the search for ideas where my hobby can be useful to people and bring me income :)

Answer 1

Great, lol. Help Vasyan earn money, he is too lazy himself.