An eye on your system
Monitor monthly internet Transmit and Receive bandwidth usage - Linux
Zenoss - Intelligent IT Operations Management
Deploy Prometheus monitoring system
Network Ping time and UPS Logger
Xplico is a Network Forensic Analysis Tool (NFAT)
Count the number of people around you by monitoring wifi signals
PotHead
Open Source SIEM
Scalable, distributed monitoring system for high-performance computing
Network performance monitoring and logging script for Cisco devices.
Monitor SNMP hosts with a sysfs-like filesystem in user-space
Batch system monitoring and archiving
Panel Indicator to interact and monitor hosts
Automated Bitcoin mining monitor and up-time enforcer
Monitoring your infrastructure for free.