1)   IsItUp Network Monitor 6.31
IsItUp Network Monitor is a server, website, port, and email system monitor. It monitors multiple IP devices, websites, servers and ports with alerts via email or pager; graphs. Web content check; performance stats and error log, runs as a service.

 2)   A1Monitor Network Monitor TCP or Web 6.1.70
Monitor multiple web or TCP servers (http, https, ftp, pop3 etc.) Receive email notification by email or pager if any can't be reached a number of times in a row

 3)   Server Nanny Network Monitor 4.0.0
Reduce downtime and be the first to know when a server or network device fails. The last time you had a network or server failure how long was it before the problem was discovered? Don't wait for employees or customers to report the problem.

 4)   PA Server Monitor Free Edition 3.1.9
PA Server Monitor has powerful features that are very simple to setup. The Free edition monitors web pages, ping response and the Windows event log, and includes several response actions such as email, reboot, etc. Monitored resource reports too.