Check out rationalwikiwikiwiki:WikiIndex. This page transcludes rationalwikiwikiwiki:Template:Wiki, which has an inputbox tag in it with urlparameter=search URL
as a parameter. That tells it to look for |search URL= in the transcluded template. So, by putting |search URL=http://wikiindex.org/, that creates a search bar to search WikiIndex. This is implemented by a hacked InputBox.classes.php using some code borrowed from ChangeWikiaEngine.php (although I probably should have borrowed from Manual:Chris_G's_botclasses/ParseMirroredWikiIndexBot.php instead, since it has more robust template parsing) along with a slightly hacked InputBox.hooks.php.
Topic on Extension talk:InputBox
Hi, I'd be interested in that. The above links (ratoinalwikiwikiwiki) do not work, is there any place this can be found?
the modified code doesn't work in MW 1.23.x...
There's no live wiki that has that hacked version installed right now. I kinda lost interest after it turned out that WikiIndex probably wasn't going to be able to use it.