Is It Down Right Now? - Network & Admin
Down Services - Get service outage alerts in real time. Know when your favourite service is offline.
UPDOWNtoday - UPDOWNTODAY allows you to check whether the website is down or not.
IsThisSiteDown.org - Free tool to check whether a site is down just for you, or for everyone.
IsItDown RightNow - "Is It Down Right Now" monitors the status of your favorite web sites and checks whether they are down or not.
Is it up? - A simple tool to check if a website or ip address is up or down.