Website monitoring services are nothing new, but many do in fact suck to use. The last monitoring service we used went down more often than our server(s) and had so many false-positives that we ditched it and vowed to give up with third-party monitoring. Then we started using Montastic which provided an extremely simple interface allowing us to get up and running in around 20 seconds, with all of our servers reporting back green (as in go!). Montastic allows monitoring for up to 100 servers/domains as well as the ability to check server status via your personal RSS feed and your very own Yahoo widget.

Read more: Montastic - Free webserver monitoring