Ping Meter Gadget - Customizable, graphical, semi-transparent ping (latency) meter.
Visualping - Visualping is the easiest to use website checker, webpage change monitoring, website change detector and website change alert software of the web. Read more about Visualping.
SmokePing - Smokeping is a tool for measuring latency.
Distill Web Monitor - Distill is a web monitoring tool. It can monitor RSS feeds, a webpage or a part of webpage. Alerts in the form of pop-up, audio or emails can be received.
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.
Update Scanner - Update Scanner is a Firefox extension to monitor web pages for updates.