Fping (open source) - fping is a program to send ICMP echo probes to network hosts, similar to ping, but much better performing when pinging multiple hosts.
Ping Meter Gadget - Customizable, graphical, semi-transparent ping (latency) meter.
NetTK - NetTK, Network Tool Kit, is an Open Source alternative for monitoring and troubleshooting your...
Open Nettest - Open Nettest is a platform for collecting, processing and visualizing data related QoS and QoE.
SmokePing - Smokeping is a tool for measuring latency.
PowerPing - Advanced command-line ping tool, lovingly inspired by Windows and Linux native tools.