1. A system, comprising: one or more computers; and a computer-readable medium coupled to the one or more computers having instructions stored thereon which, when executed by the one or more computers, cause the one or more computers to perform operations comprising: receiving an initial index, the initial index associating each application of one or more applications with one or more applications of interest, the applications being executable on a mobile computing device; for each application, receiving metadata associated with the application and receiving metadata associated with each of the one or more applications of interest; processing the metadata to selectively remove at least one of the one or more applications of interest from the initial index to provide a final index, the final index associating each application of the one or more applications with a remaining one or more applications of interest; storing the final index in computer-readable memory; receiving a user selection of a particular application of the one or more applications; retrieving the one or more applications of interest based on the particular application using the final index; and providing the one or more applications of interest for display.