BOINC - BOINC is an open-source software platform for computing using volunteered resources
Zabbix - Track, record, alert and visualize performance and availability of IT resources
Apache Mesos - Apache Mesos abstracts resources away from machines, enabling fault-tolerant and elastic distributed systems to easily be built and run effectively.
Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.
JPPF - The open source grid computing solution.
Prometheus - An open-source systems monitoring and alerting toolkit.