Internet Filters for Linux

[Dale Beams]

While I know there is filter programs for Windows (ie. CyberPatrol, etc.)
and I know I can restrict programs in linux, is there a comprehensive list
that can be used on a Linux Firewall/IP Masquarade machine that would
protect children from accessing questionable sites specified to the user.
This would allow the little one to use the internet, and still allow me to
access www.planetquake.com~ without constant worry ...