iperf - A TCP, UDP, and SCTP network bandwidth measurement tool
Technitium MAC Address Changer - Technitium MAC Address Changer (TMAC) is a freeware utility to instantly change or spoof MAC Address of any network card (NIC).
JPerf - This project gives a better UI and new functionalities to the initial JPerf 1.
Axence netTools - Axence netTools is completely free of charge, both for home and commercial use – all you have to do is to register. A tool for professionals – and others.
TamoSoft Throughput Test - TamoSoft Throughput Test is a utility for testing the performance of a wireless or wired network.
Zabbix - Track, record, alert and visualize performance and availability of IT resources