Platypus - Realtime server monitoring and reporting
SevOne - SevOne provides network managers with monitoring, troubleshooting, and performance reporting capabilities.
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.
The Dude - MikroTik is a Latvian company which was founded in 1996 to develop routers and wireless ISP systems. MikroTik now provides hardware and software for Internet connectivity in most of the countries around the world.
Nagios - Complete monitoring and alerting for servers, switches, applications, and services
Obkio - Simple Network Monitoring and Network Troubleshooting software to empower users to identify and troubleshoot network & application slowdown from the end-user perspective.