What is everyone using to remotely monitor your dedicated servers or even individual web sites?

I found a free windows based program called servers alive that I run from my PC that is connected to a cable modem. I am monitoring my phpsysinfo page and looking for specific words on the page. This confirms my server http and PHP is up and working. If it does not get a favorable response the program will send an email to my pager.

This program can be found at http://woodstone.nu/salive.

I also installed a copy of http://www.argosoft.com/ mail server to send from my local PC.

I also use the free Netstatus Script from http://scripts.tlcwe.com/ as a server status page for my customers to view the status of my servers services. An example of the output can be seen at http://www.hdllc.net/netstatus/

I am in no way affiliated with any of the software companies above, I am just trying to share some ideas and looking for additional options. Any other ideas would be appreciated and I hop this idea may help others.