iftop - iftop does for network usage what top(1) does for CPU usage.
TrafficMonitor - TrafficMonitor is a network monitoring suspension window software in Windows.
vnStat - vnStat is a console-based network traffic monitor for Linux and BSD that keeps a log of network...
NetBalancer - NetBalancer is a Windows application for local network traffic control and monitoring.
nload - Monitor network traffic and bandwidth usage in real time
NetTraffic - Essential network bandwidth monitor.