I've got an old 486 lying around (and a Celeron if I really feel like it), along with enough NICS to supply a small army (of about 3-4 people or so). I want to setup a firewall of my very own to replace the Netgear RT314 I've got working right now.
So far, I've found the following options:
I'm leaning towards SmoothWall at the moment, but I'll probably end up installing more than a couple of them before I finally settle on one.
Here's one I installed a few months ago: the NetBSD/i386 Firewall Project