SevOne - SevOne provides network managers with monitoring, troubleshooting, and performance reporting capabilities.
Platypus - Realtime server monitoring and reporting
Flowmon - Clever Network Monitoring and Security Solution based on NetFlow, IPFIX and Network Behavior Analysis
Monitornator - Server monitoring made simple
Obkio - Simple Network Monitoring and Network Troubleshooting software to empower users to identify and troubleshoot network & application slowdown from the end-user perspective.
NIXStats - SaaS monitoring tool for window/linux servers and websites. Think up-time robot but with more features.