Here are a few:
Search engines
DuckDuckGo
http://duckduckgo.com/?q=%Search%
DuckDuckGo: !Bangs
https://duckduckgo.com/bang?q=%Search%
Startpage
http://startpage.com/do/search?language=english&query=%Search%
Startpage: Past day
http://startpage.com/do/search?language=english&query=%Search%&with_date=d
Startpage: Past month
http://startpage.com/do/search?language=english&query=%Search%&with_date=m
Startpage: Past week
http://startpage.com/do/search?language=english&query=%Search%&with_date=w
Startpage: Past year
http://startpage.com/do/search?language=english&query=%Search%&with_date=y
IXQuick
http://ixquick.com/do/search?language=english&query=%Search%
Bing
http://www.bing.com/search?q=%Search%
Bing: Images
http://www.bing.com/images/search?q=%Search%
Google
http://www.google.com/search?q=%Search%
Google: Exact string
http://www.google.com/search?q=%22%Search%%22
Google: Web cache
http://webcache.googleusercontent.com/search?q=cache:%Search%
Google: Groups
http://groups.google.com/groups?q=%Search%
Youtube
http://www.youtube.com/results?search_query=%Search%
Geo search
Open Street Map
http://nominatim.openstreetmap.org/search.php?q=%Search%&polygon=1&viewbox=
Apple Maps
http://maps.apple.com/?q=%Search%
Bing Maps
http://www.bing.com/maps/?where=%Search%
Google Maps
http://maps.google.com/maps?q=%Search%
Host info
Network-Tools
http://network-tools.com/default.asp?prog=express&host=%Search%
Website subpages list
http://www.sousites.com/%Search%
Dictionaries
Wiktionary
http://en.wiktionary.org/?search=%Search%
Urban dictionary
http://www.urbandictionary.com/define.php?term=%Search%
Translation
IATE: English to any
http://iate.europa.eu/SearchByQuery.do?method=search&valid=Search+&sourceLanguage=en&targetLanguages=s&domain=0&typeOfSearch=s&request=&query=%Search%
IATE: Any to any
http://iate.europa.eu/SearchByQuery.do?method=search&valid=Search+&sourceLanguage=s&targetLanguages=s&domain=0&typeOfSearch=s&request=&query=%Search%
IATE: German to English
http://iate.europa.eu/SearchByQuery.do?method=search&valid=Search+&sourceLanguage=de&targetLanguages=en&domain=0&typeOfSearch=s&request=&query=%Search%
Linguee: English/German
http://www.linguee.com/english-german/search?source=auto&query=%Search%
Linguee: English/French
http://www.linguee.com/english-french/search?source=auto&query=%Search%
Linguee: English/Spanish
http://www.linguee.com/english-spanish/search?source=auto&query=%Search%
Leo: English/German
http://dict.leo.org/ende/index_de.html#/search=%Search%&searchLoc=0&resultOrder=expert&multiwordShowSingle=off
Bing translator (any to English)
http://www.bing.com/translator/?from=si&to=en&text=%Search%
Bing webpage translator (any to English)
http://www.microsofttranslator.com/bv.aspx?ref=Internal&a=%Search%
Google translator (any to English)
https://translate.google.com/#auto/en/%Search%
Google webpage translator (any to English)
http://translate.google.com/translate?js=n&sl=auto&tl=en&u=%Search%
Reference
Wolfram Alpha
http://www.wolframalpha.com/input/?i=%Search%
StackExchange (all)
http://stackexchange.com/search?q=%Search%
StackOverflow
http://stackoverflow.com/search?q=%Search%
Wikipedia
https://en.wikipedia.org/wiki/%Search%
IMDB
http://www.imdb.com/find?s=all&q=%Search%
Vim Wiki
http://vim.wikia.com/wiki/Special:Search?search=%Search%&fulltext=Search
CSS Tricks
https://css-tricks.com/search-results/?q=%Search%
WordPress plugins
https://wordpress.org/plugins/search.php?q=%Search%
Games
Gamespot
http://www.gamespot.com/search/?q=%Search%&indices%5B%5D=article&indices%5B%5D=review&indices%5B%5D=game
Steamprices/sales
https://www.steamprices.com/us/search/?q=%Search%&p=1
Steamprices/sales II
http://steamsales.rhekua.com/search.php?term=%Search%
iTunes & Mac App Store
Mac App Store
macappstore://search.itunes.apple.com/WebObjects/MZSearch.woa/wa/search?q=%Search%
iTunes
itms://phobos.apple.com/WebObjects/MZSearch.woa/wa/search?term=%Search%
iTunes: Artist
itms://phobos.apple.com/WebObjects/MZSearch.woa/wa/advancedSearchResults?artistTerm=%Search%
iTunes: Song
itms://phobos.apple.com/WebObjects/MZSearch.woa/wa/advancedSearchResults?songTerm=%Search%
Appshopper
http://appshopper.com/search?search=%Search%
Apple related
Apple Discussions
https://discussions.apple.com/search.jspa?q=%Search%
Ask Different
https://apple.stackexchange.com/search?q=%Search%
Keyboard Maestro Forum
https://forum.keyboardmaestro.com/search?q=%Search%
Macupdate
http://www.macupdate.com/find/mac/%Search%
MacOSXHints
http://www.macosxhints.com/search.php?query=%Search%&type=stories&mode=search&keyType=all
Shops
Amazon
https://www.amazon.com/s/?url=search-alias%3Daps&field-keywords=%Search%
Ebay
http://www.ebay.com/sch/%Search%
Local (URL schemes)
Man pages
x-man-page://%Search%
Dash
dash://%Search%
Evernote
evernote://search/%Search%
German
https://www.amazon.de/s/?url=search-alias%3Daps&field-keywords==%Search%
Dictionary
https://www.duden.de/suchen/dudenonline/%Search%
Wikipedia
https://de.wikipedia.org/wiki/%Search%