CacheGuard Gateway is a UTM, a WAF, and a QoS management appliance.
iptables mini-script in file-wizard
Anti Spam SMTP Gateway
OpenBSD based firewall distribution
Bash script to enable the firewall on startup of your Ubuntu server.
Programmable completion code (bash) for ip[6]tables (netfilter.org)
Open source voucher management / hotspot system
Programmable completion code (bash) for ipset (netfilter.org)