15. A computer-readable storage device encoded with a computer program product, the computer program product including instructions that, when executed, cause data processing apparatus to perform operations comprising: generating a language model by analyzing textual content for a first web page to determine a topic of the first web page, determining other pages determined to be directed to the same topic of the first web page, and analyzing content of queries previously submitted to the other pages determined to be directed to the same topic of the first web page, wherein the queries previously submitted to the other pages include queries submitted to respective search capabilities of at least some of the other pages; receiving, at a computer server system and from an electronic device, sound information from a user of the electronic device, and a context identifier that indicates a context within which the user provided the sound information; using the context identifier to select the generated language model from among a plurality of language models; converting speech in the sound information to text using the selected language model; and providing the text for use by the electronic device.
15. A computer-readable storage device encoded with a computer program product, the computer program product including instructions that, when executed, cause data processing apparatus to perform operations comprising: generating a language model by analyzing textual content for a first web page to determine a topic of the first web page, determining other pages determined to be directed to the same topic of the first web page, and analyzing content of queries previously submitted to the other pages determined to be directed to the same topic of the first web page, wherein the queries previously submitted to the other pages include queries submitted to respective search capabilities of at least some of the other pages; receiving, at a computer server system and from an electronic device, sound information from a user of the electronic device, and a context identifier that indicates a context within which the user provided the sound information; using the context identifier to select the generated language model from among a plurality of language models; converting speech in the sound information to text using the selected language model; and providing the text for use by the electronic device. 16. The computer-readable storage device of claim 15 , wherein the context identifier identifies a field of a form in which input on the electronic device is received, which input corresponds to the sound information.