INTERNET SEARCH ENGINES
Google
Largest database of webpages
Yahoo!
Popular search engine and subject directory
Bing
Popular search engine run by Microsoft
META-SEARCH ENGINES
Meta-search engines compile and sort results from multiple search engines.
Dogpile
Meta-search engine which brings together top results from Google, Yahoo!, and Bing
AllPlus
Meta-search engine which compiles top results from search engines like Google, Yahoo!, MSN Live, and Ask.com
CONTENT-SPECIFIC SEARCH ENGINES
Google Scholar
Google's search engine for scholarly sources
SUBJECT DIRECTORIES
Subject directories are resources for specific topics.
Academic Info Online Subject Guides
Large collection of subject guides for academic disciplines and specific research topics - list both online resources and printed reference works.
Intute
Provides access to a variety of web resources for research.
Internet Public Library (IPL2)
Collections of resources from the Internet Public Library (IPL) and the Librarians' Internet Index (LII).
Virtual Reference Shelf (Library of Congress)
Selected high-quality resources for research organized by subjects and categories.