22. The system of claim 21 , wherein: the query triggers include expansion terms, the expansion terms for each query trigger being terms that are query expansions of the one or more terms of the query trigger; identify at the client device the query triggers in the resource comprises search the resource for the query triggers included in the dictionary; and generate at the client device search query suggestions from the query triggers comprises generate for a query trigger identified in the resource a search query that includes an expansion term of the query trigger.
21. A system, comprising: a data processing apparatus; and a computer-readable storage medium coupled to the data processing apparatus, the computer-readable medium storing instructions that, when executed by the data processing apparatus, cause the data processing apparatus to perform operations comprising: sending to a client device a dictionary defining query triggers, each of the query triggers being one or more terms; sending to the client device a module executable by the client device and upon execution causes the client device to perform operations comprising: identify at the client device query triggers in a resource, the resource being a non-query resource; for each query trigger identified in the resource, calculating at the client device a rank score for the query trigger based on attributes of the query trigger, the attributes including at least one of: a context of the query trigger defined by a display format of the query trigger in the resource; and a frequency of occurrence of the query trigger in the resource; rank at the client device the query triggers according to the rank scores; generate at the client device search query suggestions from the query triggers identified in the resource; and present at the client device the search query suggestions according to the ranking of the query triggers.