Several years ago, I reviewed a lot of search engines that launched as technology showcases. To demonstrate what they could do, they’d take a large body of data and proceed to slice-n-dice it. Back then, the large body of choice seemed to be the Open Directory Project. Nowadays it seems to be Wikipedia. FUTEF, in beta at http://futef.com/, allows you to search Wikipedia both by keyword and by category.
Since I have a giant bottle of San Pellegrino on my desk I did a search for Pellegrino. I got 167 results, the first of which was for the bottled water, but in addition I also got results on the front page for locations, people, and a TV station.
(This search wasn’t too bad but with some of my other test searches I got results that were way too widespread. I would really like the ability to search for a keyword within the title of an article, or even better, within the first 50 or 100 words of an article.)
On the left side of the results there are categories by which you may narrow down your results. Some of the categories are too general to be useful (“Living People”) while others are much more specific (“Cathedrals in Italy”, “Maltese nobility”, etc.) Click on a category and the search will rerun with the category search included, and you’ll get a new set of related categories on the left side. This’ll take you a variety of places; I started with a search for bottled water and after wandering through a few category/search result pages ended up at one result for Pellegrino in a page about Gothic architecture.
In addition to the search at this site, FUTEF also offers a Firefox plugin about which you can get more information at http://futef.com/plugin/. There’s also a short blog at http://futef.blogspot.com/ and a very brief about page at http://futef.com/about.html.