We are considering approaches to using the fee-based services. Relevance factor of returned sites is high. This engine allows searches by document title and content. It operates by traversing the Web and either building an index for later use, or by searching in real-time for a query. The index built by the WebCrawler is available for searching via the WebCrawler Search Page.
Site has futher discription of search options and process.
Yahoo Keyword driven, subject oriented search service. Includes a keyword search engine, for their own datafile of linked resources. Lists by subject or search via search engine. A search engine for keyword search of titles and abstracts for a database of topical Internet resources. The database is maintained by a group of volunteer Internet monitors, librarians, etc.