It's a habit that started, I suppose, when I spent a semester interning for a literary agent, during which I read slush pile after slush pile and learned very little about the world of publishing. I did learn enough to think to start looking at the acknowledgements, looking for the name of the agent for whom I work (confession: I can't even remember her name anymore).
There are those who find the acknowledgements boring, or pointless, or too close to "inside baseball." Sure, some acknowledgements are way, way too long, and read like a laundry list of I-know-this-famous-person-and-this-one-too (Lean In, I'm looking at you, and all 7 pages of thanks). Others are the standard, relatively uninspired thankings of agents, publishers, editors, spouses, parents and children. Not that there's anything wrong with that--those people all deserve an author's thanks--but they aren't as interesting to us as readers.
As interesting as what, you might wonder?
As interesting as the unique ones, the amazing ones, the acknowledgements that a) make you want to be best friends with the author, b) let you avoid finishing the book for just *that* much longer, or c) all of the above.
a) In the acknowledgements of her third novel, Seven for a Secret, for example, author Lyndsay Faye wished for the ability to put animated gifs onto the page to express her love and appreciation for her editor and all the work put into her book. You all know you want to be best friends with Lyndsay Faye (her love of all things Sherlock Holmes doesn't hurt, of course).
Eric Smith, in the Acknowledgements for The Geek's Guide to Dating, crafts an RPG metaphor:
"If The Geek's Guide to Dating were an RPG, it would play a lot like Final Fantasy Tactics: War of the Lions. Not because this book has a hidden battle system (or does it?), but due to the sheer number of characters involved."
Confession: I do not understand the Final Fantasy reference, but this still makes me want to know Eric Smith.
b) Pam Houston kicks off the Acknowledgements section of her superb Contents May Have Shifted with more insight into the world at large, much in the style of the rest of the text of the novel:
"In the Kingdom of Bhutan, it is not enough to simply say thank you. In the language of Dzonka, a direct translation of the words used to express gratitude is, Thank you beyond the sky and the earth."
c) The acknowledgements of Joe Hill's NOS4A2 might be the best I've ever read. These pages include such insights as:
"Twitter is a hive buzzing with thought, argument, and geek-passion."
"You know who is awesome? Kate Mulgrew is awesome, for reading this book on audio."(and here's the kicker, the icing on the cake, the best part)"The Naughty List:
People who skim or outright skip acknowledgements pages. Please contact management for your free, all-expenses-paid pass to Christmasland."
In those tucked-away pages at the back of the book, I delay the inevitable end of a book I'm loving, and find keys to author personalities I'd not have seen in the text alone. I wouldn't miss them for the world.