Is It Down Right Now? - Network & Admin
Ping Meter Gadget - Customizable, graphical, semi-transparent ping (latency) meter.
UPDOWNtoday - UPDOWNTODAY allows you to check whether the website is down or not.
SmokePing - Smokeping is a tool for measuring latency.
Site Down - Site down outage and downtime reports from SiteDown.co
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.