Suggest a good free firewall

[Wyrm]

After a bit of a quick search I found these programs, which might be along the lines of what you're looking for.

http://www.r-firewall.com/
http://www.iopus.com/ipig/download/
http://www.jetico.com/ (you'll have to go to the download page and scroll down close to the bottom, but the firewall is free)