Scout Report - http://scout.cs.wisc.edu/
Internet resources, as chosen by the editorial staff of the Scout Report, cataloged and organized for efficient browsing and searching. This directory is an archive of sites reported in The Scout Report, a current awareness newsletter listing noteworthy web resources for educators and researchers.
WebCrawler - http://www.webcrawler.com
WebCrawler has been a popular search engine since 1994. Similar in setup to Lycos, it has a subject catalog of links to popular topics and a directory of reviewed web pages in addition to keyword searching. There are about 30 million pages in its index.
Yahoo! - http://www.yahoo.com
With over half a million in its index, this grand-daddy of search tools may be the largest subject directory on the web, meaning that it covers more and is less selective than other directories. It has searching both by subject and by keyword.