Open Source Monitoring System for performance and availability.
Enhanced Apache Server Status page - for one or multiple servers
Produces a graphical map of hosts, switches and routers in a network.
Zenoss - Intelligent IT Operations Management
PHP-based looking glass for Cisco, Juniper & Zebra/Quagga routers
Open source tool to monitor your servers and websites
Open Source SIEM
Dashboard of network top-talkers using netflow sources
The Energy Sensing and Monitoring Infrastructure of the GAMES project