What is a service you host you never knew you needed?
I think everybody on here is constantly keeping an eye out for what to host next. Sometimes you spinup something which chugs along nicely but sometimes you find out you've been missing out.
For me it's not very refreshing or new: Paperless-ngx. Never thought I would add all my administration to it. But it's great. I probably can't find the thing I need, but I should have a record of every mail or letter I've gotten.
Close second is Wanderer. But I would like to have a little bit more features like adding recorded routes to view speed and compare with previous walks. But that's not what it is intended for.
Easily set up, and easily attached to other things. Simple notifications about whatever is needed, like service health or updates, new posts on public platforms, etc. A simple curl is plenty to send and receive notifications, and it works on Android without requiring FCM (Google infrastructure).
If you'd permit a short quiz. Ntfy is really interesting to me. I would like to send general server updates and didn't know how to ensure users, just family and friends, get them. I think ntfy could solve that problem, right now I just text and maintain a bookstack document.
I would also like to send user specific notifications though. For example a user requests a show from Jellyseerr, the admin legally obtains said show and uploads it to jellyfin, user then gets notification that the show they requested is available.
Sadly it doesn't work with CrowdSec which is the biggest thing I would want notifications on (bans and such) and Gotify isn't the pub/sub MQTT-style that I like about ntfy...
Ntfy can act as an email server if you configure it. So if an application is not supporting ntfy directly but email, you can go that route. Ntfy will then simply forward the email as push notification. Its also pretty simple to set up, used this as a workaround because authelia doesn't support it directly. Here is the link to the specific ntfy documentation: https://docs.ntfy.sh/config/#e-mail-publishing
I used the local variant (https://docs.ntfy.sh/config/#local-only-email) which does not require any DNS entries, as I only use it for sending notifications between my self hosted containers (all on the same host).