I would create a filter rule to route traffic to a proxy server. Squid is a great free solution. Then use one of the many Squid log file parsers....like Webalizer. This will show you IP to URL.
If you want to track users to URL, then you will need a seperate solution that intergrates user authnetication and URL filtering. I use a Bluecoat applaice with the Junier routing HTTP traffic.
The Juniper, even this the URL filtering license, will not give you logs on user activity. You can get information into SYSLOG, but you will need to parse it....and I dont know of any tool to do this.