Eureka

Eureka is a set of tools which allow you to store data from HTTP logs in a database, then use a web interface to produce customised reports and "drill down" to find out more information about certain things. For instance, a report which showed the number of requests for HTML pages might have a "Who" link next to each page's request count, which would link to a list of who's been requesting that page. Likewise, a "Whence" link would show the referring sites which sent people to that page.