"Almost forgot -- I had a two-page timeline in there, too!"
See, now this is where I get confused as to what folks are talking about when they say "Author's Note". To me, elements such as a timeline, photos, extra interesting content info, further reading, sources, bibliography etc, are backmatter, and an Author's Note is backstory -- an actual note from the author written in a more personal way, where the author steps outside of the authorial book voice and speaks as the writer who created the work, talking about the research and/or writing processes, perhaps putting these elements in context. ...like on DVD bonus material, the difference between finding deleted scenes (backmatter) and a director's commentary about how he chose the cast, filmed tricky bits, and funny/sad anecdotes about the making of the movie (backstory).
I *love* backmatter, especially timelines for historical work. Verla has a fabulous double-spread timeline in ROUGH, TOUGH CHARLEY that not only puts the story in historical context, but also includes additional details and new quirky cool info for which there isn't room in the main story (in which she's already skillfully packed a ton of anecdotes and great information...it's amazing what she can fit into 32 pages!). I loved this timeline...it enriches the reading experience beautifully and I'm really glad it's there, but it stands on its own, so I would call it "backmatter", not an "Author's Note" because we're getting additional content info, but nothing about the process of acquiring or using the content.