PingPlotter - PingPlotter is a troubleshooting tool that helps IT professionals and neophytes identify, diagnose, and resolve network issues.
Ping Meter Gadget - Customizable, graphical, semi-transparent ping (latency) meter.
Open Visual Traceroute - Open source cross-platform (Windows/Linux/Mac) Java Visual Traceroute, packet sniffer and Whois.
SmokePing - Smokeping is a tool for measuring latency.
WinMTR - Free Network Diagnostic Tool. WinMTR is an equivalent of mtr for Windows.
PingInfoView - PingInfoView is a small utility that allows you to easily ping multiple host names and IP addresses, and watch the result in one table.