Any Free Tool Available For Squid & Proxy Logs Analysis in Linux ?

I have Linux (Fedora Core 5) Proxy Server Running In My Organisation. Proxy Server Has UserName & Password Authentication. I want Free or Open Source Tool So That I Can Log The Internet Activity Of Each User & Each Machine (With IP Addr.) In The LAN.
If You Guys Are Aware Of Any Such Free or Open Source Tool. Please Let Me Know.

Thanks In Advance.

What is the most usefull site on the internet?

I use Internet as a tool. I frequently visit sites as yahoo & google to use their free tools. Are there other interesting sites to visit?