1. A method of generating aggregated highlights of a digital book from a plurality of highlights, the method comprising: obtaining raw highlight intervals of a digital book from a plurality of users; reconciling the raw highlight intervals across a plurality of versions of the digital book, the reconciling comprising synchronizing the versions of the digital book and consolidating the raw highlight intervals of the synchronized versions of the digital book, at least two of the plurality of versions of the digital book differing at least without regard to the raw highlight intervals; selecting aggregated highlight intervals based on the reconciled highlight intervals using a highlight selection rule, wherein the highlight selection rule comprises: computing an overlapping interval value for the reconciled highlight intervals by counting the intersections of at least partially overlapping highlights, or generating elementary highlight intervals from reconciled highlight intervals by placing start and end values of intervals on an interval list, sorting the interval list, removing duplicates from the interval list, and building elementary highlight intervals from the resulting sorted list; creating a public version of the selected aggregated highlight intervals; creating a purchase version of the selected aggregated highlight intervals, the purchase version differing from the public version and made available based at least in part on additional compensation with respect to the public version; and displaying the public version or the purchase version of selected aggregated highlight intervals to users.