Monitornator - Server monitoring made simple

Blumira - Blumira's threat detection platform offers both automated threat detection and response, enabling organizations of any size to more efficiently defend against cybersecurity threats in near real-time.

OpsDash - All-in-one solution for monitoring servers, services, uptime and databases. Curated Dashboards. Rule-based alerting.

Google StackDriver - Stackdriver provides monitoring services for cloud-powered applications.

NIXStats - SaaS monitoring tool for window/linux servers and websites. Think up-time robot but with more features.

Devo - Devo delivers real-time operational & business value from analytics on streaming and historical data to operations.