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