Pingdom - With website monitoring from Pingdom you will be the first to know when your website is down. No installation required. 30-day free trial.
Glympse - Glympse is the easy way to safely share your location in realtime. No sign-up needed.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Zenly - Zenly is a GPS tracker to locate your friends in realtime.
Better Uptime - We call you when your website goes down
OwnTracks - Cross-platform location sharing