Here is search logs of 650,000 AOL users. It's very interesting to view search history of particular person and analyze his personality. Let's do it together! Read more about AOL search database scandal or view research papers on web searching.
www.swi-prolog.org
Stable and free standard Prolog implementation. Targeted primarily at research and education. Windows, Linux and Unix versions available. Comes with a visual debugger and a GUI environment.