33. The system of claim 29 , wherein evaluating the search results to select names of one or more identified entities of the first type comprises: ranking each identified entity based on a respective number of search result resources to which the entities are related; and selecting the names to be included in the response to the first search query based on the ranking.
29. A system comprising one or more computers and one or more storage devices storing instructions that when executed by the one or more computers cause the one or more computers to perform operations comprising: analyzing contents of each of a plurality of resources to identify entities of a first entity type that are related to the resource, wherein analyzing the contents of each of the plurality of resources comprises: identifying occurrences of names of entities in the contents of the resource, and determining that each entity whose name occurs in the resource more than a threshold number of occurrences is related to the resource; annotating each of the plurality of resources in an index database with annotations identifying the entities that are related to the resource; determining that a first search query includes a respective text reference to each of one or more predetermined attributes, wherein each attribute is associated with the first entity type; obtaining search results for the first search query from a search engine, the search results identifying a plurality of search result resources; identifying entities of the first entity type that are related to any of the plurality of search result resources identified by the search results; and selecting names of one or more of the identified entities of the first entity type to include in a response to the first search query.