Some great tips for scenarios when testing your website's search engine, from usertesting.com.
They use a range of examples, inevitably focusing mainly on e-commerce sites but the last couple are on US university sites, so well worth a look.
Top 10 ways to test internal search - article on usertesting.com
While a small number of user tests using the approaches suggested above are great - and video footage of people having an awful time will go a long way - there's also a great, free way to objectively appraise and quantify search performance. It's also a route to improvement month on month.
Site search analytics (September 2010)