gsearch.js is a JavaScript tool to add a second search box for a Google sitesearch of en.wikipedia directly under the Wikipedia search box.
Usage edit
Type the search terms into the "google search" box and click search or press enter/return to search Wikipedia using Google. A "Go" button might be added in the future to do an "I'm feeling lucky" search on Wikipedia if I can figure out how to do that with HTML/Javascript.
Installation edit
Simply add
importScript('User:Mr.Z-man/gsearch.js');
to your monobook JS page (or whatever skin you use) and bypass your cache.