1. A system, comprising: one or more computers; and a non-transitory 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 a query log, the query log comprising one or more queries corresponding to one or more applications available through an application marketplace and data, for each query, associated with the one or more applications; generating, for each query, a map to at least one application of the one or more applications based on the query log; determining, for each map, a weight of each application of the one or more applications based on the data associated with the respective application; determining for at least one of the one or more applications, a co-weight of one or more applications of interest based on the weight of each application of the one or more applications; based on the co-weight of the one or more applications of interest, generating an index of co-weights of applications, the index of co-weights of applications associating the at least one of the one or more applications to the one or more applications of interest; storing the index of co-weights of applications 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 index of co-weights of applications; and providing the one or more applications of interest for display.