ClickZ has the details of a Patricia Seybold Group study which says that for e-commerce sites, the top two-percent of search queries conducted within the site are the most important. The top four-percent of search queries conducted on non-ecommerce sites are the most important. If you improve the searcher experience for those top 4 or 2 percent of your internal site searches, half of all searchers will be happier.
So if you can mine the top four-percent of your internal searches and start in order to make those results better, you can greatly improve your searcher’s experience. Specifically with a site you are trying to sell on, if you can improve those top queries, you will more likely convert on a sale. Happy searchers are 2.7 times more likely to convert on your site.