Zabbix - Track, record, alert and visualize performance and availability of IT resources
NetSpeedMonitor - NetSpeedMonitor is a lightweight Network Monitoring Toolbar for your Windows Taskbar
Observium - Observium
NetWorx - NetWorx is a simple and powerful tool that helps you objectively evaluate your bandwidth situation.
Nagios - Complete monitoring and alerting for servers, switches, applications, and services
TrafficMonitor - TrafficMonitor is a network monitoring suspension window software in Windows.