Ask HN: Which Slack integrations do you use?

As a Slack App developer myself, I'm very curious to learn what really work for people. I went to multiple Slack events where they present use-cases from their customers, but all that stuff has gone through a good amount of marketing "improvements".

I'd like to ask the HN audience what REALLY works for you?

Here's a bit about what I use or I've seen being used:

- Trello notifications - even though trello sends me a load of push-notifications, #trello-update is somehow the first place where I look.

- HubSpot live chat - Replying to live chat discussions right from Slack is 10x easier than opening the app

- Jenkins, Sentry, Rollbar alerts - of course

- Standuply - we don't really use it in my current team, but I've seen it being adopted at my previous workplace so I'll leave it here.