There is also a search done against Yahoo using its categories to filter the response. The results are too tight. I know that there are sites missed here. Often it is best to compare results with several search engines. In last class we discussed the tricks used by the search engines to achieve profitability.
Some searches are seeded.
Web sites that depend on hit count for soliciting advertising support often pay the search engine for placement. Webmasters often try through keywords placed in their page headers to improve their placement on the listings that would result in specific searches. By the repeated use of certain keywords they improve their relevancy. An unethical and self-defeating trick would be to use multiple occurences of a popular search term even though it has no application to the page. All of this jostling for position has led to the creation of sites that monitor search engine performance .