OK I searched this forum to make sure this hasn't been introduced brefore - so apologies if it has.
But I have come across this firewall called pfSense
http://www.pfsense.org/
It is loosely based on M0n0wall, and is set up in the same manner as smoothwall, IP Cop etc etc
It is still in its testing stage, I believe but I have heard some pretty favourable comments from those who have used it. I'm not yet using it myself as I need another box to set it up on but going on what I have read so far I will be switching as soon as they have a stable release.
Worth keeping an eye on.
cheers
floppy