You already have a syslog server. One is built-in to every version of Mac OS X. It's the system that builds the standard system logs (well, technically, it's not syslog, per se. since it's an Apple-developed log server, but it follows the syslog standards, so for all intents and purposes, it counts).
The main caveat is that the log daemon, by default, only accepts log messages from the machine itself, not network clients. You'll need to edit the configuration to support network logging.
The logging process is managed by launchd, and it's configuration file is at /System/Library/LaunchDaemons/com.apple.syslogd.plist
If you check this file you'll see a commented section that talks about network logging:
Un-comment the following lines to enable the network syslog protocol listener.
Uncomment this section to enable the network listener, then just point your firewall to log to your server's IP address.
OK, you totally lost me.
Do you mean recording, or logging the web sites? as per your original request?
If so - I already answered that - you ALREADY have a log server installed on your machine. You need to edit the configuration (as I explained) to enable network logging, then configure your firewall to send its logs to your server.
The logs will be written in /var/log/ and you can use Console.app to view them.
Sorry my bad. I understand the process I need to do to be able to log the websites visited by people on my network. I was just wondering if there was a fancy program which would look at this data and tell me things like:
On Monday's between 8:00am and 11:00am the website Facebook was visited 500 times. etc.