• Google
  Extremely fast, ordered searches. Also, try the new and expanding list of features, including unit conversion, maps and more.
  Search syntax cheatsheet.
  
• AltaVista
  Search World Wide Web and Usenet newsgroup articles
  
  
• AllTheWeb
  FAST search and retrieval of web pages and files
  Claims to have largest index of pages of all the search tools
  
  
• Google Groups
  formerly DejaNews, 20-year Usenet Archive with
  over 700 million messages
  
  
• Yahoo
  Search WWW and Usenet articles or browse the directory
  
  
• HotBot
  WWW and Usenet searches
  
  
• NorthernLight
  Searches collections of documents accessible for a fee
  
  
• SurfWax
  Offers additional keywords with which to narrow results.
  
  
• Teoma
  Ranks results based on the number of same-subject pages that reference it.
  
  
• NOAA Search
  Searches concentrating on information from NOAA sites
  
  
• FirstGov
  Searchable and browsable Government information portal
  

• Vivisimo
  Meta search engine with organized results
  
  
• MetaCrawler
  Automatically query all of the major search engines
  
  
• Mamma
  Automatically query all of the major search engines
  
  

Search science-oriented sites for literature in print and web-only format...

• IODE OceanPortal
  The OceanPortal is a high-level directory of Ocean Data and Information related web sites. Its objective is to help scientists and other ocean experts in locating such data & information.
  
  
• Scirus
  Free science-only search portal by Elsevier Inc. It currently covers the Web, the ScienceDirect database (containing 1,200 journals), BioMedNet, ChemWeb, Neuroscion and Medline. Multiple electronic document formats are included.
  
  
• arXiv.org e-Print archive
  Maintained by the Los Alamos National Laboratory. Covers mainly physics and mathematics.
  
  
• Cite Seer
  The current database focuses on computer science articles. The software is available (no cost for non-commercial use) if you would like to create a database in another area.
  
• Biology Browser
  From Thomson owners of BIOSIS.
  
• Resource Discovery Network - A portal to selected sources of scientific information organized in collaboration with over 70 educational and research organizations in the UK.
  

• Open Directory
  Topical directories assembled by volunteer experts
  
  
• Librarians' Index to the Internet
  A searchable, annotated subject directory of Internet resources selected and evaluated by librarians for their usefulness to users of public libraries.
  
• Internet Public Library
  The Washington State-centric version of LII.
  

Search Tips
Hints, tips, and a tutorial on searching the web

More Search Tips
Hints and tips for Google, FAST/AllTheWeb, and NorthernLight

Top Level Domain (TLD) suffix codes for all URLs
what does ".com" mean and how are they assigned?