An all inclusive web monitoring service.
Healthchecks.io - Monitor your cron jobs and scheduled tasks, get notified when they fail.
DownDetector - A simple service to tell you whether a website is down.
Pingbreak - Pingbreak is an original and free monitoring service.
Outage.Report - See if your provider or web service is having an outage or it's just you. Post yours and see other's reports and complaints
IsItDown RightNow - "Is It Down Right Now" monitors the status of your favorite web sites and checks whether they are down or not.
Silent Down - Silent Down is a website uptime and performance monitoring platform - Get notified instantly if your site is down or having performance issues.