Nagios (formerly Netsaint) is a daemon written in C that is designed
to monitor networked hosts and services.
Links
See Blue, a port of Nagios to Java.
OpenIPMI is an effort to create a full-function IPMI system to allow full access to all IPMI information on a server and to abstract it to a level that will make it easy to use.
IPMI: Intelligent Platform Management Interface