11. A non-transitory computer storage media encoded with one or more computer programs, the one or more computer programs comprising instructions that when executed by data processing apparatus cause the data processing apparatus to perform operations comprising: receiving trigger query data, the trigger query data identifying one or more trigger queries and one or more sets of authoritative users, each set of authoritative users being associated with a respective trigger query; generating a plurality of trigger query and authoritative user pairs, each trigger query and authoritative user pair identifying a trigger query and an authoritative user from a set of authoritative users associated with the trigger query; for at least one trigger query and authoritative user pair: generating a snippet based on user data, the user data being associated with the authoritative user in one or more computer-implemented services, the snippet being specific to the trigger query and specific to the authoritative user, and determining that the snippet is insufficient, and in response, modifying the snippet to provide a revised snippet; and storing one or more snippets including the revised snippet in computer-readable memory, each snippet being specific to a respective trigger query and authoritative user pair, for which the respective snippet was generated.
11. A non-transitory computer storage media encoded with one or more computer programs, the one or more computer programs comprising instructions that when executed by data processing apparatus cause the data processing apparatus to perform operations comprising: receiving trigger query data, the trigger query data identifying one or more trigger queries and one or more sets of authoritative users, each set of authoritative users being associated with a respective trigger query; generating a plurality of trigger query and authoritative user pairs, each trigger query and authoritative user pair identifying a trigger query and an authoritative user from a set of authoritative users associated with the trigger query; for at least one trigger query and authoritative user pair: generating a snippet based on user data, the user data being associated with the authoritative user in one or more computer-implemented services, the snippet being specific to the trigger query and specific to the authoritative user, and determining that the snippet is insufficient, and in response, modifying the snippet to provide a revised snippet; and storing one or more snippets including the revised snippet in computer-readable memory, each snippet being specific to a respective trigger query and authoritative user pair, for which the respective snippet was generated. 12. The computer storage media of claim 11 , wherein generating a snippet based on user data comprises: retrieving a plurality of text pieces associated with the authoritative user, each text piece having been generated from the user data; identifying one or more snippet pieces from the plurality of text pieces based on the trigger query; and appending two or more snippet pieces together to provide the snippet.