utility for viewing sites visited

We've recently been having issues with certain users visiting
unauthorized sites. My supervisor has asked me to set up some method
of tracking where these users go and getting the time stamp. My first
thought was I could finally use squid.
But, I am wondering if there are any tools out there that could log
all sites and visits and then render the results in some sort of web
page that we could then peruse.
I have checked freshmeat.net, but was overwhelmed by the many tools
available. Any one have any good experience with any certain tool?
Thanks.
KJ