Is It Down Right Now? - Network & Admin
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.
Site Down - Site down outage and downtime reports from SiteDown.co
SmokePing - Smokeping is a tool for measuring latency.
IsThisSiteDown.org - Free tool to check whether a site is down just for you, or for everyone.
PingPlotter - PingPlotter is a troubleshooting tool that helps IT professionals and neophytes identify, diagnose, and resolve network issues.