I think a basic thing is the "users who installed this installed also..." feature. Search results should be sortable e.g. by popularity, release date, rating, most commented etc.. To provide even better search results you need to build some kind of ontology, which helps to prioritize results and to find correct answers even if search words do not match. Ontologies contain e.g. parent and sibling relations of content, and ideally this information would be from maemo.org users. Maintaing this kind of information is too big a task for administrators.