Not OP, but we have numerous integrations. Technical, corporate, and fun. GitHub, Jira, Status Hero, Outlook Calendar, Asana, Conference Booking, polls, "water cooler" type apps, and more. I actually can't get a comprehensive list right now because Slack is down...
We could make do without many of these integrations if we had to but the integrations and webhooks are THE killer feature to me. Chat is easy to solve.