Fantasy series seem like they've gotten longer and longer and it's often years between volumes. Many authors have started doing recaps of their previous books at the start of later volumes, but not all.
I could see this being useful for that.
I could see this being useful for that.
I can also imagine a character interaction graph, animated by chapter.
Oh, and pronunciation. The Sun Eater series is eloquent, but the names are inscrutable without having heard a few of the audio books.