Nagios is one of the best open source IT infrastructure monitoring system available in market. The thing that makes it so powerful are the addons that can enhance its capabilities and give it some teeth. One such addon which is awesome in my view and one of the best I have seen recently is the Nagmap addon. It uses map from google map api version 3, and you don’t need a key for it. The installation is easy and you only need to know about latitude and longitude of the places you show up on the map (you can use Google to get those).