1)   WebWatchBot Website Monitoring Software 5.1.2
Constant monitoring is critical to ensuring your website and web-based applications are error free and performing with acceptable response times. WebWatchBot 5.0 is the leading software solution for performance monitoring and problem notification.

 2)   SiteUp 1.1
SiteUp monitors your web sites and warns you when any become unreachable (e.g. when a server crashes). Because it checks page content it can even detect when the server is OK, but a site or page is unavailable.