Nagios - Complete monitoring and alerting for servers, switches, applications, and services
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.
Gitwin - Enable your Windows system as a powerful and secure Git repository. Supports ssh, http(s) transports. Gitweb with highlighter and gravatar support available.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
System Center Operations Manager - System Center Operations Manager 2012 R2 uniquely enables customers to reduce the cost of data...
Better Uptime - We call you when your website goes down