1u-Firewall.com brings you tutorials and links for all things on a 1u server
The latest tutorials are a bunch of squid howto tutorials for limiting access to the internet. For example limiting internet access to lunch time, banning Internet Explorer or setting up a transparent squid server on openbsd.
Please note that the tutorials are still in a very rough state and haven't been thoroughly checked but they might push you in the right direction if stuck.