Enhanced Apache Server Status page - for one or multiple servers
Fritz!Box SmartHome Monitoring with PRTG and AHA-Interface
Xplico is a Network Forensic Analysis Tool (NFAT)
PotHead
Open Source SIEM
Open source tool to monitor your servers and websites
Scalable, distributed monitoring system for high-performance computing
network control and reporting
Batch system monitoring and archiving
Monitoring your infrastructure for free.
Manage your ISC DHCPD service