Firewall Projects
m0n0wall
m0n0wall is a project aimed at creating a complete, embedded firewall software package that, when used together with an embedded PC, provides all the important features of commercial firewall boxes at a fraction of the price.
ComixWall
ComixWall is developed on OpenBSD and ports/packages, which are licensed under BSD, GPL, or a similar open source license. ComixWall is, to my knowledge, the first fully open source ISG running on OpenBSD. ComixWall is freely available for all, and it already has most of the advanced features of many commercial and closed-source.