Search Completion
Vimium supports search completion for custom search engines (not for the default search engine). Search completion is activated whenever the search URL of a custom search engine matches one of the completion engines built into Vimium.
To activate search completion, type o to activate vomnibar and then type the search completion keyword as defined in settings (such as 'g') and press space.
Here are a couple of examples of how the vomnibar looks with search completion.
Here is a list of some example custom search engines for which completion is available.
# Wikipedia.
w: http://en.wikipedia.org/w/index.php?title=Special:Search&search=%s Wikipedia
# Google.
g: https://www.google.ie/search?q=%s Google
l: https://www.google.ie/search?btnI&q=%s I'm feeling lucky...
gm: https://www.google.ie/maps?q=%s Google maps
# Youtube.
y: http://www.youtube.com/results?search_query=%s Youtube
#DuckDuckGo
d: https://duckduckgo.com/?ia=about&q=%s DuckDuckGo
# Amazon
az: http://www.amazon.co.uk/s/?field-keywords=%s Amazon
# Dictionary (Merriam-Webster).
dw: http://www.merriam-webster.com/dictionary/%s Merriam-Webster
# Bing
b: https://www.bing.com/search?q=%s Bing
Completion engines are not hard to write, but pull requests contributing new ones are unlikely to be merged unless they are for a particularly popular provider.
For details and examples, see completion_engines.js.
Search completion is available for custom search engines only, not for the default search engine. Nevertheless, you can get search completion for your default search engine by adding it also as a custom search engine. For example:
g: https://www.google.com/search?q=%s Google