1. A method comprising: maintaining transaction data indicative of online transactions in which a population of subscribers have engaged over time, wherein the transaction data indicates respectively for each of a plurality of transactions (i) which subscriber engaged in the transaction, (ii) when the transaction occurred, (iii) where the subscriber was located when engaging the transaction, and (iv) what content was a subject of the transaction; a custom content server using the transaction data as a basis to select content to background-download to a given subscriber, in view of a current location of the given subscriber and in view of the current time, wherein using the transaction data as a basis to select content to background-download to a given subscriber in view of a current location of the given subscriber and in view of the current time comprises (a) determining the current location of the given subscriber, (b) determining the current time, (c) searching through the transaction data to find a set of one or more transaction records matching the determined location and time, (d) for each transaction record of the set, assigning a score respectively to each of a plurality of pieces of available content based on a comparison of the piece of available content to the content indicated by the transaction record, and (e) using the assigned scores as a basis to select one or more pieces of available content to background-download to the given subscriber; and the custom content server background-downloading the selected content to the given subscriber.