Monitor Web site availability and get notified upon downtime and error conditions.
Webmon is a Web site availability monitoring and escalation service that allows you to monitor your online services and get notified upon downtime and error conditions. Webmon also offers realtime dashboards to compare service performances in realtime and take action when needed and custom triggers to detect various anomalies.
A very low cost user friendly web monitor, has plenty of features, and allows for various monitors on various protocols. It allows you to easily set up alerts and gets me up to date on my site uptime, if you are on the web, you should not tolerate any downtime.
Cons
Would like to see an API, and integration capabilities with other tools.
Summary
For excellent online web monitoring low cost tool, this is the tool to use!