Internet Connectivity Monitor - This a lightweight program that provides you with a way to monitor your internet connection uptime.
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.
PuTTY - Popular free terminal application. Mostly used as an SSH client.
SmokePing - Smokeping is a tool for measuring latency.
PingPlotter - PingPlotter is a troubleshooting tool that helps IT professionals and neophytes identify, diagnose, and resolve network issues.
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.