Here are the web search engines that I have found most useful. QueryServer has been particularly useful because of the way it sorts the results into categories.

Search Engines Standard Search

Advanced Search

Google http://www.google.com/ http://www.google.com/advanced_search
All The Web http://alltheweb.com/ http://www.alltheweb.com/advanced
Alta Vista http://altavista.com/ http://www.altavista.com/sites/search/adv
     

Metasearch Engines
(these make use of other search engines)

   
QueryServer http://queryserver.com/web.htm  
Mamma http://www.mamma.com/ http://www.mamma.com/psearch.html
MetaCrawler http://www.metacrawler.com/ http://www.metacrawler.com/info.metac/search/advance.htm
     
News Group Search Engines    
DejaNews - now part of Google http://dejanews.com/