Its good to know when Your sites down. I share with You some free uptime tools.
Free Website Monitoring Service | Web Server Monitor
Internetseer - Website Monitoring and Web Server Monitoring Service
Free Website Uptime Monitoring - Uptime Robot
Free Web Server Health and Uptime Monitoring
Website monitoring, server monitoring, monitor uptime by Uptrends
Free website monitoring service: Montastic
Pingdom Website monitoring. Monitor your server and network uptime and performance for free.