59. The computer-readable medium of claim 53 , wherein the set of aggregated commands comprises a command that specifies a document collection in which to conduct a search.
53. A computer-readable medium encoded with a computer program comprising commands that, when executed, operate to cause a computer to perform operations comprising: receiving multiple context files from one or more third-party content providers, wherein each set of commands contains one or more commands for controlling an operation of the search engine in processing a search query input and in presenting search results, each context file is one of a plurality of predefined context files; receiving in a search engine the search query input, the search query input received from an interface provided by one of the third party content providers; aggregating the commands in the multiple context files into a set of aggregated commands; using the aggregated commands to control an organization and a presentation of the search results resulting from the processing of the search query input, including: processing the search query input using the aggregated commands to produce a context processed search query; generating context processed search results responsive to the context processed search query; and providing the context processed search results in accordance with the aggregated commands.