Statsignal - Statsignal is a simple and cost-effective way to monitor your website or server and publish a status page of your system.
iperf - A TCP, UDP, and SCTP network bandwidth measurement tool
OnlineOrNot - Uptime monitoring for software teams (even teams of one).
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...
Site monitoring - Free open-source website monitoring software, easy to set up and use for monitoring web sites.
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.