Suprvise is a real-time health monitoring and errors tracking dashboard.
Down Services - Get service outage alerts in real time. Know when your favourite service is offline.
WebGazer - Monitor your website's availability with WebGazer, review its performance and get instant notifications when your website goes down. No installation required and free plan available.
UPDOWNtoday - UPDOWNTODAY allows you to check whether the website is down or not.
Monitority - Simple website monitoring service (sms/email alerts)
IsItDown RightNow - "Is It Down Right Now" monitors the status of your favorite web sites and checks whether they are down or not.
Hyperping - Cheap uptime and performance monitoring with detailed reporting and flexible alerting