A nice description for interWiki links (from Wikipedia.org):

InterWiki is a facility for creating links to the many wiki wiki webs on the World Wide Web. Users avoid pasting in entire URLs (as they would for regular web pages) and instead use a shorthand similar to links within the same wiki.

DokuWiki supports InterWiki using the following syntax:

[[interWikiId>targetTopic|Text]]

• interWikiId is the unique Id of the wiki or remote site.
• targetTopic could be a name of a page, a search query or a wiki topic depending on the corresponding URL of the interWikiId.

The following InterWiki links are currently available:

# Google
Google          http://www.google.com/search?q=
GoogleGroups    http://groups.google.com/groups?q=
Go              http://www.google.com/search?q={URL}&btnI=lucky

# Answers
WP              http://en.wikipedia.org/wiki/
WikiPedia       http://www.wikipedia.com/wiki/
IMDB            http://us.imdb.com/Title?
Acronym         http://www.acronymfinder.com/af-query.asp?String=exact&Acronym=
JargonFile      http://sunir.org/apps/meta.pl?wiki=JargonFile&redirect=
PhpFn           http://www.php.net/{NAME}

# Open-Source
SourceForge     http://sourceforge.net/{NAME}

# qooxdoo
Bug             http://bugzilla.qooxdoo.org/show_bug.cgi?id={NAME}
DevelList         http://article.gmane.org/gmane.comp.lang.javascript.qooxdoo.devel/{NAME}

# Doku Wiki
SB              http://www.splitbrain.org/go/
Doku            http://wiki.splitbrain.org/
Man             http://man.splitbrain.org/index.php/man/
Xref            http://dev.splitbrain.org/reference/dokuwiki/{NAME}.html

# Books
Amazon          http://www.amazon.com/exec/obidos/ASIN/

# Other
Freecache       http://freecache.org/{NAME}
RFC             http://www.cs.ccu.edu.tw/~chm91u/rfc2html.php?loc=remote&number=