Is It Down Right Now? - Network & Admin
UPDOWNtoday - UPDOWNTODAY allows you to check whether the website is down or not.
Site Down - Site down outage and downtime reports from SiteDown.co
Is it up? - A simple tool to check if a website or ip address is up or down.
downinspector.com - Find out if a website is down for everyone or just you.
IsZDown - Monitor the errors and status of the most popular websites and apps. Check whether they are down right now or not.