CacheGuard Gateway is a UTM, a WAF, and a QoS management appliance.
Image of OpenWrt OS, with snort community featured in.
Anti Spam SMTP Gateway
Xplico is a Network Forensic Analysis Tool (NFAT)
Count the number of people around you by monitoring wifi signals
Open Source SIEM
Automated Bitcoin mining monitor and up-time enforcer
A simple TCP/UDP Port Flooder written in Python.