StatusNotify - StatusNotify monitors the status of 250+ cloud services.
Site Down - Site down outage and downtime reports from SiteDown.co
IsDown App - Monitor all your cloud services status pages in one place
Is it Down? - Is it down can check if a website is down or is it just your PC that can not access it.
DownDetector - A simple service to tell you whether a website is down.
UPDOWNtoday - UPDOWNTODAY allows you to check whether the website is down or not.