MonAMI aims to be a standard place for monitoring the availability and performance of services. It can talk to many different monitoring systems while remaining easy to configure. It has a plugin structure, making it easy to add new things to monitor or to integrate with new monitoring systems.
Network UPS Tools (also known as NUT) is an extremely powerful and versatile client/server based approach to UPS monitoring. Products from a wide range of vendors (APC, Belkin, Best Power, MGE, Tripp-Lite, etc.) are supported. A shared UPS can be monitored by one host, notifcations being sent to the other hosts via authenticated TCP connections. A Web interface is available, as is a Windows client.
Power Daemon (powerd) is a daemon that can monitor a UPS and safely shut down the machine when the power is out. It can also notify other power daemons running on the network that the power is out, so they may also safely shutdown. It can automatically determine the UPS and cable configurations.