11. A system, comprising: an augmentation query data store storing augmentation queries; a cached search results store storing search results, each stored search result being related to at least one of the stored augmentation queries; one or more computers; and software stored in a computer readable medium and comprising instructions executable by the one or more computers to cause the one or more computers to perform operations comprising: identifying structured document data in a document, the structured document data including information identifying one or more entities and, for each entity, a resource locator specifying a resource location of a resource for the entity; determining one or more terms associated with a particular entity of the one or more entities, the determining the one or more terms comprising: identifying anchor text in the structured document data, the anchor text including the one or more terms; determining a number of documents in a set of documents that include the identified anchor text; and determining that the number of documents exceed a threshold number of documents; generating one or more synthetic queries from the structured document data, the generating comprising generating a synthetic query that includes the anchor text; storing the synthetic query in the augmentation query data store; identifying search results that are relevant to the synthetic query; associating, in the augmentation query data store, the identified search results and the resource for the particular entity with the synthetic query; and storing at least a portion of the identified search results and a search result for the resource for the particular entity in the cached search results store for use in an augmented search operation, wherein the stored portion of the identified search results are provided with other search results in response to the augmented search operation, the other search results being responsive to a received query for which the augmented search operation is performed.
11. A system, comprising: an augmentation query data store storing augmentation queries; a cached search results store storing search results, each stored search result being related to at least one of the stored augmentation queries; one or more computers; and software stored in a computer readable medium and comprising instructions executable by the one or more computers to cause the one or more computers to perform operations comprising: identifying structured document data in a document, the structured document data including information identifying one or more entities and, for each entity, a resource locator specifying a resource location of a resource for the entity; determining one or more terms associated with a particular entity of the one or more entities, the determining the one or more terms comprising: identifying anchor text in the structured document data, the anchor text including the one or more terms; determining a number of documents in a set of documents that include the identified anchor text; and determining that the number of documents exceed a threshold number of documents; generating one or more synthetic queries from the structured document data, the generating comprising generating a synthetic query that includes the anchor text; storing the synthetic query in the augmentation query data store; identifying search results that are relevant to the synthetic query; associating, in the augmentation query data store, the identified search results and the resource for the particular entity with the synthetic query; and storing at least a portion of the identified search results and a search result for the resource for the particular entity in the cached search results store for use in an augmented search operation, wherein the stored portion of the identified search results are provided with other search results in response to the augmented search operation, the other search results being responsive to a received query for which the augmented search operation is performed. 13. The system of claim 11 , wherein the operation of identifying search results that are relevant to the synthetic query comprises the operations of: identifying a domain name of a resource location that matches one or more terms in the synthetic query; identifying the document at the resource location for referencing in a search result for the synthetic query; and associating the document with the synthetic query so that the document is identified as a search result responsive to a user query that matches the synthetic query.