This site went down for about an hour a couple of weeks ago (my host’s database server had problems, I’m told). Fortunately, I didn’t have to wait for someone to email me and tell me my site was down because a free service I’ve been using for more than a year alerted me promptly that something was wrong.
Exactly what is mon.itor.us?
mon.itor.us provides a “24 x 7” network and website monitoring service to help its users quickly identify faults and deficiencies to ensure continuous operations of their IT infrastructure and maintain business operations that provide the ultimate web experience. Particularly mon.itor.us provides personalized Ajax dashboard interface, checks server performance and availability, generates uptime reports, tracks visitors, checks CPU, memory and other systems resources, and alerts its users in case abnormalities are detected. External end-user checks are performed from geographically dispersed servers as well from customer locations. Internal checks can be performed inside of network firewalls through smart agents.
Alerts are delivered via email and/or RSS. I receive mine via email and set my Gmail account to forward alerts to my cell phone so I know as soon as possible if there is a problem with my site and am alerted when it gets back to normal.