UPDOWNtoday - UPDOWNTODAY allows you to check whether the website is down or not.
Ping Meter Gadget - Customizable, graphical, semi-transparent ping (latency) meter.
IsThisSiteDown.org - Free tool to check whether a site is down just for you, or for everyone.
SmokePing - Smokeping is a tool for measuring latency.
Is it Down? - Is it down can check if a website is down or is it just your PC that can not access it.
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.