PagerDuty is an incident management system for IT monitoring, delivering alerting, on-call scheduling, policies for escalation and tracking of incidents to maximize uptime. PagerDuty offers solutions for all kinds of teams, including DevOps teams, transition to DevOps and enterprise teams. PagerDuty provides the resources to sort through data from monitoring systems, uncover issues, and handle critical issues efficiently.
PagerDuty works great with almost all monitoring tools including: Nagios, Icinga, Keynote, New Relic, Pingdom, Cloudkick, Circonus, Splunk, Zenoss, Monit, Munin, SolarWinds and many others. If it can send email, it works with PagerDuty.