To put my two cents in, I have been investigating m0n0wall
(http://m0n0.com/) for about six months now. I have it running on my home
firewall (pc engines WRAP platform http://pcengines.ch) and have loaded it
on a number of old Nokia IP330 boxes for testing.
A fork of the project to also look at is pfSense (http://pfsense.com/) which
is based on m0n0wall. pfSense is much more flexible in terms of add-on
packages, is designed with a failover option, and multi-WAN support to name
a few things. Then again how much do you want loaded on a firewall which is
a topic for a whole different discussion.
There is active development on both projects and both seem very usable.
Andrew
