TrafficMonitor - TrafficMonitor is a network monitoring suspension window software in Windows.
KNemo - KNemo displays for every network interface an icon in the systray.
NetSpeedMonitor - NetSpeedMonitor is a lightweight Network Monitoring Toolbar for your Windows Taskbar
DU Meter - DU Meter is a network bandwidth monitor for your computer.
FreeMeter - Monitor network bandwidth (C#.NET 2k/XP+). Desktop and Systray graph.
Smart Traffic Meter - Smart Traffic Meter is a Linux network usage monitor.