1. A method implemented in a computing system for ranking items in a query result, the method comprising: under control of one or more computer systems configured with executable instructions, receiving a query specifying one or more terms; generating a query result identifying items satisfying the query; for each of the items identified in the query result, combining ratings reflecting both (a) the frequencies with which users selected the item in query results produced for earlier queries specifying one or more terms of the query and (b) levels of effort required to make such selections, such that the combination of ratings produces a ranking value for the item, the level of effort associated with selecting an item being based on an amount of effort required to select the item relative to amounts of effort required to select other items identified in the query result, wherein if a greater level of effort is required to select an item, a higher rating is associated with the item; and displaying the items identified by the generated query result in accordance with their produced ranking values.