1. A handheld electronic book reader device comprising: a processor; memory storing a collection of one or more electronic books; an index module stored in the memory and executable on the processor of the handheld electronic book reader device to generate searchable indices of the one or more electronic books at the handheld electronic book reader device; and searchable indices stored in the memory and comprising a searchable item index of terms in one of the electronic books and a searchable master index of terms in the collection of one or more electronic books, wherein the master index comprises a list of terms used in electronic books in the collection and, for each term, a reference to one or more item index entries for the respective term, and wherein each reference to an item index entry comprises an identifier of the electronic book in which the term appears, a number of times the term appears in the respective electronic book, and a position at which the term is indexed in the item index for the respective electronic book.