Search Engines

http://www.searchengineshowdown.com/
http://searchenginewatch.com/
http://searchengineland.com/

WEB:

http://www.google.com/
http://search.yahoo.com/
http://www.live.com/
http://www.ask.com/

http://www.gigablast.com/
http://www.exalead.com/
http://www.cuil.com/
http://www.entireweb.com/

http://www.hakia.com/
http://www.powerset.com/

http://www.mahalo.com/

http://search.wikia.com/

http://clusty.com/

http://a9.com/

http://www.surfwax.com/

http://www.baidu.com/
http://www.yandex.ru/

http://www.dogpile.com/

http://www.alexa.com/

http://www.blekko.com/ (by skrenta creator of www.topix.net)

Vertical:

http://citeseer.ist.psu.edu/ http://citeseerx.ist.psu.edu/
http://dblp.uni-trier.de/
http://www.elsevier.com/ http://www.scirus.com/ http://www.sciencedirect.com/
http://scholar.google.com/
http://www.nlsearch.com/
http://www.questia.com/

Deep Web:

http://www.deepdyve.com/

(http://www.nlsearch.com/, http://www.science.gov/, http://www.closerlooksearch.com/)

Human search engines;

http://www.mahalo.com/
http://www.chacha.com/

Social search engines:

http://www.oneriot.com/ (based on Yahoo index)
http://scour.com/
http://www.qitera.com/

News:

http://www.topix.com/
http://techmeme.com/
http://searchenginewatch.com/2156261

Blogs:

http://technorati.com/
http://www.icerocket.com/
http://www.bloglines.com/
http://www.blogdigger.com/
http://www.blogscope.net/

Video:

http://en.wikipedia.org/wiki/Video_search_engine
http://cid-2d044dc4a5aa3245.skydrive.live.com/self.aspx/.Public/Multimedia[1].pdf

Images:

http://tineye.com/
http://www.picsearch.com/
http://www.pixsta.co.uk/ http://www.pixsta.com/

Encyclopedias and Magazines:

http://www.encyclopedia.com/

http://findarticles.com/

http://findarticles.com/

Digital Libraries:

http://www.europeana.eu/

Online Communities - Professional Knowledge About Information Technology:

http://www.ittoolbox.com/

Wikipedia Search Engines:

http://www.wikiwax.com/
http://wiki.lumrix.net/en/

Categorization:

http://www.kosmix.com/

http://en.wikipedia.org/wiki/Kosmix