1. Return first the results which exactly match the search terms.
2. Do not include results where one or more of the search terms only exists in an advert on the page.
3. Re-introduce a feature which an early search engine (I think it was AltaVista) where you could specify a search term to be 'near' another.
4. (more important in languages other than English) Allow you to specify that any tense, person or case of a search term be matched (eg if searching in French, *aller would match any of 'vais', 'vas', 'va', 'allons', 'allez', 'irai', 'allâmes' etc)
5. Allow you to restrict the results to those where he search terms are actually rendered on the page when you follow the link.