I have been working with SQL Server for several years, but am new to my role of Database Administrator. Currently, we do not have a central monitoring system. Each server "checks in" by email on a regular basis so I know that if I don't get the email something has gone wrong.

I would like to have a central monitoring server that will alert me if something goes wrong with any of the other servers. That part is simple enough, but I would also like something monitoring the monitoring server. Are there any third party or hosted solutions that I could use for this? What is the best practice? I want something that will notify me even if our entire network goes dark.