Hyperping - Cheap uptime and performance monitoring with detailed reporting and flexible alerting
Trello for Slack - Organize anything with anyone, inside Slack
Suprvise - Know instantly when your sites are down.
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Oh Dear! - Website monitoring, without the hassle
Halp - Slack-first ticketing for internal helpdesk