I’ve been on the look-out for open source firewall software recently.  For your benefit, here’s a list of what I’ve found so far:

pfSense – http://www.pfsense.com/

m0n0wall – http://m0n0.ch/wall/

IPCop – http://sourceforge.net/apps/trac/ipcop/wiki

Untangle – http://www.untangle.com/

Zeroshell – http://www.zeroshell.net/eng/

I also ran across a very interesting web-based SSL VPN:

OpenVPN ALS (a.k.a as Adito) – http://sourceforge.net/projects/openvpn-als/