1. A method comprising: receiving, at a server computer and via a network, a recommendation request requesting an electronic media item be served to a first electronic account; determining, by the server computer, that music preference data associated with the first electronic account is unable to recommend an electronic music item; obtaining, by the server computer, a plurality of application preference clusters that are each associated with an electronic application preference profile, wherein the application preference clusters are created by a first clustering operation that clusters a first population of electronic accounts into the application preference clusters based on software applications purchased online by each of the first population of electronic accounts; selecting from the application preference clusters and by the server computer, a first application preference cluster associated with a first electronic application preference profile for the first electronic account, wherein the first electronic application preference profile corresponds to the first electronic account at an application preference strength level determined from similarities between the first electronic application preference profile and applications purchased by the first electronic account; obtaining, by the server computer, a plurality of music preference clusters that are each associated with an electronic music preference profile, wherein the music preference clusters are created by a second clustering operation that clusters a second population of electronic accounts into music preference clusters based on online music preference data for the second population of electronic accounts; identifying, by the server computer, a preference relationship between the first application preference cluster and a first music preference cluster, wherein the preference relationship is associated with a preference relationship strength value that indicates a likelihood that an account within the first application preference cluster is also part of the first music preference cluster; identifying, by the server computer, a first electronic music preference profile for the first music preference cluster to be used for recommending electronic media items for the first electronic account based on the application preference strength level and the preference relationship strength value; and selecting, by the server computer, at least one electronic music item to be served to the first electronic account based on the identified first electronic music preference profile.