My group and I have developed a block that does a search within all course activities/resources. This is not a global search for the site, but at least it does take care of searching inside of courses.
Can be downloaded here: https://moodle.org/plugins/view.php?plugin=block_course_search
Search oohoo in the plugins page to find other contributions. (https://moodle.org/plugins/search.php?s=oohoo)