iperf - A TCP, UDP, and SCTP network bandwidth measurement tool
JPerf - This project gives a better UI and new functionalities to the initial JPerf 1.
netperf - Netperf is a benchmark that can be used to measure the performance of many different types of networking. It provides tests for both unidirectional throughput, and end-to-end latency. - HewlettPack...
NetStress - NetStress is a user-friendly benchmarking tool that is mostly used by networking professionals to measure the network performance of both wired and wireless connections.
jsPerf - A performance playground for JavaScript developers. Easily create and share test cases and run cross-browser benchmarks to find out which code snippet is most efficient.
TamoSoft Throughput Test - TamoSoft Throughput Test is a utility for testing the performance of a wireless or wired network.