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. See the SourceForge page for the source code.
What is Zenoss?
The Zenoss project provides an integrated, easy-to-deploy and cost-effective opensource alternative for enterprise IT infrastructure monitoring. Unlike the big OSS companies (IBM, HP, CA, BMC, Amdocs) we are able to keep costs down and directly involve end users throughout the world. More details can be found here.
Lithium is a single-application solution for network, server and appliance monitoring. With a stunning monitoring console for both Mac OS X and Windows, Lithium is an end-to-end solution for monitoring your network infrastructure.
ZABBIX offers advanced monitoring, alerting and visualisation features today which are missing in other monitoring systems, even some of the best commercial ones.