iperf - A TCP, UDP, and SCTP network bandwidth measurement tool
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.
JPerf - This project gives a better UI and new functionalities to the initial JPerf 1.
benchmark.js - A benchmarking library that supports high-resolution timers & returns statistically significant results.
TamoSoft Throughput Test - TamoSoft Throughput Test is a utility for testing the performance of a wireless or wired network.
NetIO-GUI - NetIO-GUI is a Windows frontend for the multiplatform commandline utility 'netio'.